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Singh V, Ouellette SP. Altering the redox status of Chlamydia trachomatis directly impacts its developmental cycle progression. eLife 2025; 13:RP98409. [PMID: 39819645 PMCID: PMC11741522 DOI: 10.7554/elife.98409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2025] Open
Abstract
Chlamydia trachomatis is an obligate intracellular bacterial pathogen with a unique developmental cycle. It differentiates between two functional and morphological forms: the elementary body (EB) and the reticulate body (RB). The signals that trigger differentiation from one form to the other are unknown. EBs and RBs have distinctive characteristics that distinguish them, including their size, infectivity, proteome, and transcriptome. Intriguingly, they also differ in their overall redox status as EBs are oxidized and RBs are reduced. We hypothesize that alterations in redox may serve as a trigger for secondary differentiation. To test this, we examined the function of the primary antioxidant enzyme alkyl hydroperoxide reductase subunit C (AhpC), a well-known member of the peroxiredoxins family, in chlamydial growth and development. Based on our hypothesis, we predicted that altering the expression of ahpC would modulate chlamydial redox status and trigger earlier or delayed secondary differentiation. Therefore, we created ahpC overexpression and knockdown strains. During ahpC knockdown, ROS levels were elevated, and the bacteria were sensitive to a broad set of peroxide stresses. Interestingly, we observed increased expression of EB-associated genes and concurrent higher production of EBs at an earlier time in the developmental cycle, indicating earlier secondary differentiation occurs under elevated oxidation conditions. In contrast, overexpression of AhpC created a resistant phenotype against oxidizing agents and delayed secondary differentiation. Together, these results indicate that redox potential is a critical factor in developmental cycle progression. For the first time, our study provides a mechanism of chlamydial secondary differentiation dependent on redox status.
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Affiliation(s)
- Vandana Singh
- Department of Pathology, Microbiology, and Immunology, College of Medicine, University of Nebraska Medical CenterOmahaUnited States
| | - Scot P Ouellette
- Department of Pathology, Microbiology, and Immunology, College of Medicine, University of Nebraska Medical CenterOmahaUnited States
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Fan J, Mo X, Zhang H, Xu L, Yin J, Wan F. Identification of the organic peroxide scavenging system of Yersinia pseudotuberculosis and its regulation by OxyR. Appl Environ Microbiol 2024; 90:e0146824. [PMID: 39264182 PMCID: PMC11497825 DOI: 10.1128/aem.01468-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2024] [Accepted: 08/19/2024] [Indexed: 09/13/2024] Open
Abstract
Oxidative stress caused by reactive oxygen species (ROS) is inevitable for all aerobic microorganisms as ROS are the byproducts of aerobic respiration. For gut pathogens, ROS are an integrated part of colonization resistance which protects the host against bacteria invasion. Alkyl hydroperoxide reductase (AhpR) and organic hydroperoxide resistance (Ohr) proteins are considered as the main enzymes responsible for the degradation of organic peroxides (OPs) in most bacteria. To elucidate how enteric pathogen Yersinia pseudotuberculosis YPIII deals with oxidative stress induced by OPs, we performed transcriptomic analysis and identified the OP scavenging system, which is composed of glutathione peroxidase (Gpx), thiol peroxidase (Tpx), and AhpR. Gpx serves as the main scavenger of OPs, and Tpx assists in the degradation of OPs. Transcriptional factor OxyR regulates Gpx expression, suggesting that OxyR is the regulator mediating the cellular response to OPs. Although AhpR has little influence on OP degradation, its deletion would greatly impair the scavenging ability of OPs in the absence of gpx or tpx. In addition, we found that catalase KatG and KatE are responsive to OPs but do not participate in the removal of OPs.IMPORTANCEIn bacteria, oxidative stress caused by ROS is a continuously occurring cellular response and requires multiple genes to participate in this process. The elimination of OPs is mainly dependent on AhpR and Ohr protein. Here, we carried out transcriptomic analysis to search for enzymes responsible for the removal of organic peroxides in Yersinia pseudotuberculosis. We found that Gpx was the primary OP scavenger in bacteria, which was positively regulated by the oxidative stress regulator OxyR. The OP scavenging system in Y. pseudotuberculosis was composedof Gpx, Tpx, and AhpR. OxyR is the critical global regulator mediating gene expression involved in OPs and H2O2 stress. These findings suggest that Y. pseudotuberculosis has a unique defense system in response to oxidative stress.
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Affiliation(s)
- Junfeng Fan
- School of Laboratory Medicine and Biotechnology, Hangzhou Medical College, Hangzhou, China
- Key Laboratory of Biomarkers and In Vitro Diagnosis Translation of Zhejiang Province, Hangzhou, China
| | - Xiaofen Mo
- School of Laboratory Medicine and Biotechnology, Hangzhou Medical College, Hangzhou, China
- Key Laboratory of Biomarkers and In Vitro Diagnosis Translation of Zhejiang Province, Hangzhou, China
| | - Hui Zhang
- School of Laboratory Medicine and Biotechnology, Hangzhou Medical College, Hangzhou, China
- Key Laboratory of Biomarkers and In Vitro Diagnosis Translation of Zhejiang Province, Hangzhou, China
| | - Linna Xu
- School of Laboratory Medicine and Biotechnology, Hangzhou Medical College, Hangzhou, China
| | - Jianhua Yin
- Institute of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Fen Wan
- School of Laboratory Medicine and Biotechnology, Hangzhou Medical College, Hangzhou, China
- Key Laboratory of Biomarkers and In Vitro Diagnosis Translation of Zhejiang Province, Hangzhou, China
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Singh V, Ouellette SP. Altering the redox status of Chlamydia trachomatis directly impacts its developmental cycle progression. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.26.591247. [PMID: 39464112 PMCID: PMC11507673 DOI: 10.1101/2024.04.26.591247] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/29/2024]
Abstract
Chlamydia trachomatis is an obligate intracellular bacterial pathogen with a unique developmental cycle. It differentiates between two functional and morphological forms: elementary body (EB) and reticulate body (RB). The signals that trigger differentiation from one form to the other are unknown. EBs and RBs have distinctive characteristics that distinguish them, including their size, infectivity, proteome, and transcriptome. Intriguingly, they also differ in their overall redox status as EBs are oxidized and RBs are reduced. We hypothesize that alterations in redox may serve as a trigger for secondary differentiation. To test this, we examined the function of the primary antioxidant enzyme alkyl hydroperoxide reductase subunit C (AhpC), a well-known member of the peroxiredoxins family, in chlamydial growth and development. Based on our hypothesis, we predicted that altering the expression of ahpC would modulate chlamydial redox status and trigger earlier or delayed secondary differentiation. To test this, we created ahpC overexpression and knockdown strains. During ahpC knockdown, ROS levels were elevated, and the bacteria were sensitive to a broad set of peroxide stresses. Interestingly, we observed increased expression of EB-associated genes and concurrent higher production of EBs at an earlier time in the developmental cycle, indicating earlier secondary differentiation occurs under elevated oxidation conditions. In contrast, overexpression of AhpC created a resistant phenotype against oxidizing agents and delayed secondary differentiation. Together, these results indicate that redox potential is a critical factor in developmental cycle progression. For the first time, our study provides a mechanism of chlamydial secondary differentiation dependent on redox status.
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Kandari D, Joshi H. PerR: A Peroxide Sensor Eliciting Metal Ion-dependent Regulation in Various Bacteria. Mol Biotechnol 2024:10.1007/s12033-024-01266-8. [PMID: 39294512 DOI: 10.1007/s12033-024-01266-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2024] [Accepted: 08/20/2024] [Indexed: 09/20/2024]
Abstract
Bacteria have to thrive in difficult conditions wherein their competitors generate partially reduced forms of oxygen, like hydrogen peroxide and superoxides. These oxidative stress molecules can also arise from within via the autoxidation of redox enzymes. To adapt to such conditions, bacteria express detox enzymes as well as repair proteins. Transcription factors regulate these defenses, and PerR is one of them. PerR is a Fur family transcriptional regulator that senses peroxide stress. Metal-bound PerR (either Mn2+ or Fe2+) can repress transcription of its regulon, but only the Fe2+-bound form of PerR can sense H2O2. This review describes different aspects of PerR and its varied roles, specifically in bacterial pathogens. Despite having roles beyond sensing peroxides, it is an underrated regulator that needs to be explored more deeply in pathogens.
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Affiliation(s)
- Divya Kandari
- School of Biotechnology, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Hemant Joshi
- School of Biotechnology, Jawaharlal Nehru University, New Delhi, 110067, India.
- Division of Experimental Medicine, University of California, San Francisco, CA, 94107, USA.
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Wu S, Chen Y, Chen Z, Wei F, Zhou Q, Li P, Gu Q. Reactive oxygen species and gastric carcinogenesis: The complex interaction between Helicobacter pylori and host. Helicobacter 2023; 28:e13024. [PMID: 37798959 DOI: 10.1111/hel.13024] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 09/10/2023] [Accepted: 09/21/2023] [Indexed: 10/07/2023]
Abstract
Helicobacter pylori (H. pylori) is a highly successful human pathogen that colonizes stomach in around 50% of the global population. The colonization of bacterium induces an inflammatory response and a substantial rise in the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS), mostly derived from host neutrophils and gastric epithelial cells, which play a crucial role in combating bacterial infections. However, H. pylori has developed various strategies to quench the deleterious effects of ROS, including the production of antioxidant enzymes, antioxidant proteins as well as blocking the generation of oxidants. The host's inability to eliminate H. pylori infection results in persistent ROS production. Notably, excessive ROS can disrupt the intracellular signal transduction and biological processes of the host, incurring chronic inflammation and cellular damage, such as DNA damage, lipid peroxidation, and protein oxidation. Markedly, the sustained inflammatory response and oxidative stress during H. pylori infection are major risk factor for gastric carcinogenesis. In this context, we summarize the literature on H. pylori infection-induced ROS production, the strategies used by H. pylori to counteract the host response, and subsequent host damage and gastric carcinogenesis.
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Affiliation(s)
- Shiying Wu
- Key Laboratory for Food Microbial Technology of Zhejiang Province, College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, China
| | - Yongqiang Chen
- Key Laboratory for Food Microbial Technology of Zhejiang Province, College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, China
| | - Ziqi Chen
- Key Laboratory for Food Microbial Technology of Zhejiang Province, College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, China
| | - Fangtong Wei
- Key Laboratory for Food Microbial Technology of Zhejiang Province, College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, China
| | - Qingqing Zhou
- Key Laboratory for Food Microbial Technology of Zhejiang Province, College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, China
| | - Ping Li
- Key Laboratory for Food Microbial Technology of Zhejiang Province, College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, China
| | - Qing Gu
- Key Laboratory for Food Microbial Technology of Zhejiang Province, College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, China
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Sawant S, Baldwin TC, Metryka O, Rahman A. Evaluation of the Effect of Plectranthus amboinicus L. Leaf Extracts on the Bacterial Antioxidant System and Cell Membrane Integrity of Pseudomonas aeruginosa PA01 and Staphylococcus aureus NCTC8325. Pathogens 2023; 12:853. [PMID: 37375543 DOI: 10.3390/pathogens12060853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 06/08/2023] [Accepted: 06/19/2023] [Indexed: 06/29/2023] Open
Abstract
Plectranthus amboinicus (Indian borage) has been extensively studied for its medicinal properties, which can be exploited to develop new antimicrobial therapeutics. The current study investigated the effect of Plectranthus amboinicus leaf extracts on the catalase activity, reactive oxygen species, lipid peroxidation, cytoplasmic membrane permeability, and efflux pump activity in S. aureus NCTC8325 and P. aeruginosa PA01. As the enzyme catalase protects bacteria against oxidative stress, disruption of its activity creates an imbalance in reactive oxygen species (ROS) levels, which subsequently oxidizes lipid chains, leading to lipid peroxidation. In addition, bacterial cell membranes are a potential target for new antibacterial agents, as efflux pump systems play a crucial role in antimicrobial resistance. Upon exposure of the microorganisms to Indian borage leaf extracts, the observed catalase activity decreased by 60% and 20% in P. aeruginosa and S. aureus, respectively. The generation of ROS can cause oxidation reactions to occur within the polyunsaturated fatty acids of the lipid membranes and induce lipid peroxidation. To investigate these phenomena, the increase in ROS activity in P. aeruginosa and S. aureus was studied using H2DCFDA, which is oxidized to 2',7'-dichlorofluorescein (DCF) by ROS. Furthermore, the concentration of lipid peroxidation product (malondialdehyde) was assessed using the Thiobarbituric acid assay and was shown to increase by 42.4% and 42.5% in P. aeruginosa and S. aureus, respectively. The effect of the extracts on the cell membrane permeability was monitored using diSC3-5 dye and it was observed that the cell membrane permeability of P. aeruginosa increased by 58% and of S. aureus by 83%. The effect on efflux pump activity was investigated using Rhodamine-6-uptake assay, which displayed a decrease in efflux activity of 25.5% in P. aeruginosa and 24.2% in S. aureus after treatment with the extracts. This combination of different methods to study various bacterial virulence factors provides a more robust, mechanistic understanding of the effect of P. amboinicus extracts on P. aeruginosa and S. aureus. This study thus represents the first report of the assessment of the effect of Indian borage leaf extracts on bacterial antioxidant systems and bacterial cell membranes, and can facilitate the future development of bacterial resistance modifying agents derived from P. amboinicus.
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Affiliation(s)
- Sheeba Sawant
- Faculty of Science and Engineering, University of Wolverhampton, Wulfruna St., Wolverhampton WV1 1LY, UK
| | - Timothy C Baldwin
- Faculty of Science and Engineering, University of Wolverhampton, Wulfruna St., Wolverhampton WV1 1LY, UK
| | - Oliwia Metryka
- Doctoral School, University of Silesia, Bankowa 14, 40-032 Katowice, Poland
| | - Ayesha Rahman
- Faculty of Science and Engineering, University of Wolverhampton, Wulfruna St., Wolverhampton WV1 1LY, UK
- School of Healthcare, College of Life Sciences, University of Leicester, Leicester LE1 7RH, UK
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Loh JT, Shuman JHB, Lin AS, Favret N, Piazuelo MB, Mallal S, Chopra A, McClain MS, Cover TL. Positive Selection of Mutations in the Helicobacter pylori katA 5' Untranslated Region in a Mongolian Gerbil Model of Gastric Disease. Infect Immun 2022; 90:e0000422. [PMID: 35652648 PMCID: PMC9302185 DOI: 10.1128/iai.00004-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Accepted: 05/11/2022] [Indexed: 01/18/2023] Open
Abstract
To evaluate potential effects of gastric inflammation on Helicobacter pylori diversification and evolution within the stomach, we experimentally infected Mongolian gerbils with an H. pylori strain in which Cag type IV secretion system (T4SS) activity is controlled by a TetR/tetO system. Gerbils infected with H. pylori under conditions in which Cag T4SS activity was derepressed had significantly higher levels of gastric inflammation than gerbils infected under conditions with repressed Cag T4SS activity. Mutations in the 5' untranslated region (UTR) of katA (encoding catalase) were detected in strains cultured from 8 of the 17 gerbils infected with Cag T4SS-active H. pylori and none of the strains from 17 gerbils infected with Cag T4SS-inactive H. pylori. Catalase enzymatic activity, steady-state katA transcript levels, and katA transcript stability were increased in strains with these single nucleotide polymorphisms (SNPs) compared to strains in which these SNPs were absent. Moreover, strains harboring these SNPs exhibited increased resistance to bactericidal effects of hydrogen peroxide, compared to control strains. Experimental introduction of the SNPs into the wild-type katA 5' UTR resulted in increased katA transcript stability, increased katA steady-state levels, and increased catalase enzymatic activity. Based on site-directed mutagenesis and modeling of RNA structure, increased katA transcript levels were correlated with higher predicted thermal stability of the katA 5' UTR secondary structure. These data suggest that high levels of gastric inflammation positively select for H. pylori strains producing increased levels of catalase, which may confer survival advantages to the bacteria in an inflammatory gastric environment.
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Affiliation(s)
- John T. Loh
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Jennifer H. B. Shuman
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Aung Soe Lin
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Natalie Favret
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - M. Blanca Piazuelo
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Simon Mallal
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
- Institute for Immunology and Infectious Diseases, Murdoch University, Murdoch, Australia
| | - Abha Chopra
- Institute for Immunology and Infectious Diseases, Murdoch University, Murdoch, Australia
| | - Mark S. McClain
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennesse, USA
| | - Timothy L. Cover
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennesse, USA
- Veterans Affairs Tennessee Valley Healthcare System, Nashville, Tennessee, USA
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Hnatush SO, Maslovska OD, Komplikevych SY, Kovbasa IV. Influence of cobalt chloride and ferric citrate on purple non-sulfur bacteria Rhodopseudomonas yavorovii. BIOSYSTEMS DIVERSITY 2022. [DOI: 10.15421/012204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Heavy metals that enter the environment due to natural processes or industrial activities, when accumulated, have a negative impact on organisms, including microorganisms. Microorganisms have developed various adaptations to heavy metal compounds. The aim of our work was to investigate the influence of ferric citrate and cobalt (II) chloride on biomass accumulation, indicators of free radical damage and activity of enzymes of the antioxidant defense system of bacteria Rhodopseudomonas yavorovii IMV B-7620, that were isolated from the water of Yavorivske Lake (Ukraine, Lviv region), which was formed as a result of flooding of a sulfur quarry. We used cultural, photometric methods, and statistical processing of the results was performed using two-way ANOVA and factor analysis. It was found that ferric citrate at a concentration of 1–12 mM causes inhibition of the accumulation of biomass of bacteria Rh. yavorovii IMV B-7620 up to 44.7%, and cobalt (II) chloride at a concentration of 1–15 mM – up to 70.4%, compared with the control. The studied concentrations of ferric citrate and cobalt (II) chloride cause free radical damage to lipids and proteins of Rh. yavorovii IMV B-7620. As a result of two-way ANOVA we found that under the influence of ferric citrate statistically significant changes in biomass accumulation, lipid hydroperoxides and thiobarbiturate reactive species content, superoxide dismutase activity were predetermined by increasing the concentration of metal salts as well as increasing the duration of cultivation of bacteria, while the content of diene conjugates and catalase activity changed with increasing duration of cultivation. Under the influence of cobalt (II) chloride, statistically significant changes in all studied indicators were found both due to the increase in the concentration of metal salts and with increasing duration of bacterial cultivation. The studied parameters of Rh. yavorovii IMV B-7620 cells under the influence of ferric citrate and cobalt (II) chloride are combined into two factors, that explain 95.4% and 99.2% of the total data variance, respectively. Under the influence of ferric citrate, the first latent factor included diene conjugates, thiobarbiturate reactive species, carbonyl groups in proteins, which are closely linked by a direct bond and inversely related to the content of lipid hydroperoxides and catalase activity. The second latent factor included duration of cultivation of bacteria, biomass accumulation, and superoxide dismutase activity, which are inversely related to lipid hydroperoxide content and catalase activity. Under the influence of cobalt (II) chloride, the first latent factor included the content of lipid hydroperoxides, carbonyl groups in proteins, as well as catalase and superoxide dismutase activities, which are inversely related to bacterial biomass.
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Tairum CA, Santos MC, Breyer CA, de Oliveira ALP, Cabrera VIM, Toledo-Silva G, Mori GM, Toyama MH, Netto LES, de Oliveira MA. Effects of Serine or Threonine in the Active Site of Typical 2-Cys Prx on Hyperoxidation Susceptibility and on Chaperone Activity. Antioxidants (Basel) 2021; 10:1032. [PMID: 34202406 PMCID: PMC8300647 DOI: 10.3390/antiox10071032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 06/02/2021] [Accepted: 06/10/2021] [Indexed: 11/23/2022] Open
Abstract
Typical 2-Cys peroxiredoxins (2-Cys Prx) are ubiquitous Cys-based peroxidases, which are stable as decamers in the reduced state, and may dissociate into dimers upon disulfide bond formation. A peroxidatic Cys (CP) takes part of a catalytic triad, together with a Thr/Ser and an Arg. Previously, we described that the presence of Ser (instead of Thr) in the active site stabilizes yeast 2-Cys Prx as decamers. Here, we compared the hyperoxidation susceptibilities of yeast 2-Cys Prx. Notably, 2-Cys Prx containing Ser (named here Ser-Prx) were more resistant to hyperoxidation than enzymes containing Thr (Thr-Prx). In silico analysis revealed that Thr-Prx are more frequent in all domains of life, while Ser-Prx are more abundant in bacteria. As yeast 2-Cys Prx, bacterial Ser-Prx are more stable as decamers than Thr-Prx. However, bacterial Ser-Prx were only slightly more resistant to hyperoxidation than Thr-Prx. Furthermore, in all cases, organic hydroperoxide inhibited more the peroxidase activities of 2-Cys Prx than hydrogen peroxide. Moreover, bacterial Ser-Prx displayed increased thermal resistance and chaperone activity, which may be related with its enhanced stability as decamers compared to Thr-Prx. Therefore, the single substitution of Thr by Ser in the catalytic triad results in profound biochemical and structural differences in 2-Cys Prx.
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Affiliation(s)
- Carlos A. Tairum
- Instituto de Biociências, Universidade Estadual Paulista, UNESP, São Vicente 01049-010, Brazil; (C.A.T.); (M.C.S.); (C.A.B.); (A.L.P.d.O.); (V.I.M.C.); (M.H.T.)
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo 01049-010, Brazil
| | - Melina Cardoso Santos
- Instituto de Biociências, Universidade Estadual Paulista, UNESP, São Vicente 01049-010, Brazil; (C.A.T.); (M.C.S.); (C.A.B.); (A.L.P.d.O.); (V.I.M.C.); (M.H.T.)
| | - Carlos Alexandre Breyer
- Instituto de Biociências, Universidade Estadual Paulista, UNESP, São Vicente 01049-010, Brazil; (C.A.T.); (M.C.S.); (C.A.B.); (A.L.P.d.O.); (V.I.M.C.); (M.H.T.)
| | - Ana Laura Pires de Oliveira
- Instituto de Biociências, Universidade Estadual Paulista, UNESP, São Vicente 01049-010, Brazil; (C.A.T.); (M.C.S.); (C.A.B.); (A.L.P.d.O.); (V.I.M.C.); (M.H.T.)
| | - Vitoria Isabela Montanhero Cabrera
- Instituto de Biociências, Universidade Estadual Paulista, UNESP, São Vicente 01049-010, Brazil; (C.A.T.); (M.C.S.); (C.A.B.); (A.L.P.d.O.); (V.I.M.C.); (M.H.T.)
| | - Guilherme Toledo-Silva
- Laboratório de Biomarcadores de Contaminação Aquática e Imunoquímica, Departamento de Bioquímica, Universidade Federal de Santa Catarina, Florianópolis 88040-900, Brazil;
| | - Gustavo Maruyama Mori
- Laboratório de Ecologia Molecular, Instituto de Biociências, Universidade Estadual Paulista, UNESP, São Vicente 01049-010, Brazil;
| | - Marcos Hikari Toyama
- Instituto de Biociências, Universidade Estadual Paulista, UNESP, São Vicente 01049-010, Brazil; (C.A.T.); (M.C.S.); (C.A.B.); (A.L.P.d.O.); (V.I.M.C.); (M.H.T.)
| | - Luis Eduardo Soares Netto
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo 01049-010, Brazil
| | - Marcos Antonio de Oliveira
- Instituto de Biociências, Universidade Estadual Paulista, UNESP, São Vicente 01049-010, Brazil; (C.A.T.); (M.C.S.); (C.A.B.); (A.L.P.d.O.); (V.I.M.C.); (M.H.T.)
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Fasnacht M, Polacek N. Oxidative Stress in Bacteria and the Central Dogma of Molecular Biology. Front Mol Biosci 2021; 8:671037. [PMID: 34041267 PMCID: PMC8141631 DOI: 10.3389/fmolb.2021.671037] [Citation(s) in RCA: 104] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 04/26/2021] [Indexed: 11/13/2022] Open
Abstract
Ever since the "great oxidation event," Earth's cellular life forms had to cope with the danger of reactive oxygen species (ROS) affecting the integrity of biomolecules and hampering cellular metabolism circuits. Consequently, increasing ROS levels in the biosphere represented growing stress levels and thus shaped the evolution of species. Whether the ROS were produced endogenously or exogenously, different systems evolved to remove the ROS and repair the damage they inflicted. If ROS outweigh the cell's capacity to remove the threat, we speak of oxidative stress. The injuries through oxidative stress in cells are diverse. This article reviews the damage oxidative stress imposes on the different steps of the central dogma of molecular biology in bacteria, focusing in particular on the RNA machines involved in transcription and translation.
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Affiliation(s)
- Michel Fasnacht
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland.,Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Norbert Polacek
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland
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Gobert AP, Wilson KT. Polyamine- and NADPH-dependent generation of ROS during Helicobacter pylori infection: A blessing in disguise. Free Radic Biol Med 2017; 105:16-27. [PMID: 27682363 PMCID: PMC5366100 DOI: 10.1016/j.freeradbiomed.2016.09.024] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 09/16/2016] [Accepted: 09/23/2016] [Indexed: 12/20/2022]
Abstract
Helicobacter pylori is a Gram-negative bacterium that specifically colonizes the gastric ecological niche. During the infectious process, which results in diseases ranging from chronic gastritis to gastric cancer, the host response is characterized by the activation of the innate immunity of gastric epithelial cells and macrophages. These cells thus produce effector molecules such as reactive oxygen species (ROS) to counteract the infection. The generation of ROS in response to H. pylori involves two canonical pathways: 1) the NADPH-dependent reduction of molecular oxygen to generate O2•-, which can dismute to generate ROS; and 2) the back-conversion of the polyamine spermine into spermidine through the enzyme spermine oxidase, leading to H2O2 production. Although these products have the potential to affect the survival of bacteria, H. pylori has acquired numerous strategies to counteract their deleterious effects. Nonetheless, ROS-mediated oxidative DNA damage and mutations may participate in the adaptation of H. pylori to its ecological niche. Lastly, ROS have been shown to play a major role in the development of the inflammation and carcinogenesis. It is the purpose of this review to summarize the literature about the production of ROS during H. pylori infection and their role in this infectious gastric disease.
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Affiliation(s)
- Alain P Gobert
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, United States; Center for Mucosal Inflammation and Cancer, United States
| | - Keith T Wilson
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, United States; Department of Pathology, Microbiology, and Immunology, United States; Department of Cancer Biology, United States; Center for Mucosal Inflammation and Cancer, United States; Vanderbilt Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, TN 37232, United States; Veterans Affairs Tennessee Valley Healthcare System, Nashville, TN 37212, United States.
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12
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Kayıhan DS, Kayıhan C, Çiftçi YÖ. Excess boron responsive regulations of antioxidative mechanism at physio-biochemical and molecular levels in Arabidopsis thaliana. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2016; 109:337-345. [PMID: 27794275 DOI: 10.1016/j.plaphy.2016.10.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 10/10/2016] [Accepted: 10/16/2016] [Indexed: 05/07/2023]
Abstract
This work was aimed to evaluate the effect of boron (B) toxicity on oxidative damage level, non-enzymatic antioxidant accumulation such as anthocyanin, flavonoid and proline and expression levels of antioxidant enzymes including superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT) and glutathione reductase (GR) and their respective activities as well as expression levels of miR398 and miR408 in Arabidopsis thaliana. Plants were germinated and grown on MS medium containing 1 mM B (1B) and 3 mM B (3B) for 14 d. Toxic B led to a decrease of photosynthetic pigments and an increase in accumulation of total soluble and insoluble sugars in accordance with phenotypically viewed chlorosis of seedlings through increasing level of B concentration. Along with these inhibitions, a corresponding increase in contents of flavonoid, anthocyanin and proline occurred that provoked oxidative stress tolerance. 3B caused a remarkable increase in total SOD activity whereas the activities of APX, GR and CAT remained unchanged as verified by expected increase in H2O2 content. In contrast to GR, the coincidence was found between the expressions of SOD and APX genes and their respective activities. 1B induced mir398 expression, whereas 3B did not cause any significant change in expression of mir408 and mir398. Expression levels of GR genes were coordinately regulated with DHAR2 expression. Moreover, the changes in expression level of MDAR2 was in accordance with changes in APX6 expression and total APX activity, indicating fine-tuned regulation of ascorbate-glutathione cycle which might trigger antioxidative responses against B toxicity in Arabidopsis thaliana.
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Affiliation(s)
- Doğa Selin Kayıhan
- Department of Molecular Biology and Genetics, Gebze Technical University, Kocaeli, Turkey
| | - Ceyhun Kayıhan
- Department of Molecular Biology and Genetics, Gebze Technical University, Kocaeli, Turkey
| | - Yelda Özden Çiftçi
- Department of Molecular Biology and Genetics, Gebze Technical University, Kocaeli, Turkey.
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13
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Mori G, Doniselli N, Faroldi F, Percudani R. Heme binding and peroxidase activity of a secreted minicatalase. FEBS Lett 2016; 590:4495-4506. [PMID: 27859138 DOI: 10.1002/1873-3468.12493] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 10/29/2016] [Accepted: 11/07/2016] [Indexed: 11/10/2022]
Abstract
Microbial pathogens often require efficient and robust H2 O2 scavenger activities to survive in the presence of reactive oxygen species generated by inflammatory responses. In addition to catalases and peroxidases, enzymes known to scavenge H2 O2 , a novel class of secreted minicatalases is found in diderm bacteria. Here, we characterize the Helicobacter pylori (Hp) minicatalase: a monomeric hemoprotein with catalase core homology. Overexpression of Hp minicatalase rescued a catalase/peroxidase-deficient Escherichia coli phenotype under aerobic conditions and limited H2 O2 stress. The purified enzyme lacks catalase activity, but has strong (kcat > 100 s-1 ) H2 O2 -dependent peroxidase activity toward a variety of organic substrates. Our investigations into heme binding revealed that the heme cofactor is assembled in the periplasm to form the functional holoprotein. Furthermore, we observed the presence of a disulfide bond near the heme cavity of Hp minicatalase, which is conserved in secreted minicatalases and, therefore, may play a role in heme binding.
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Affiliation(s)
- Giulia Mori
- Department of Life Sciences, University of Parma, Italy
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14
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Benoit SL, Maier RJ. Helicobacter Catalase Devoid of Catalytic Activity Protects the Bacterium against Oxidative Stress. J Biol Chem 2016; 291:23366-23373. [PMID: 27605666 DOI: 10.1074/jbc.m116.747881] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 08/30/2016] [Indexed: 01/18/2023] Open
Abstract
Catalase, a conserved and abundant enzyme found in all domains of life, dissipates the oxidant hydrogen peroxide (H2O2). The gastric pathogen Helicobacter pylori undergoes host-mediated oxidant stress exposure, and its catalase contains oxidizable methionine (Met) residues. We hypothesized catalase may play a large stress-combating role independent of its classical catalytic one, namely quenching harmful oxidants through its recyclable Met residues, resulting in oxidant protection to the bacterium. Two Helicobacter mutant strains (katAH56A and katAY339A) containing catalase without enzyme activity but that retain all Met residues were created. These strains were much more resistant to oxidants than a catalase-deletion mutant strain. The quenching ability of the altered versions was shown, whereby oxidant-stressed (HOCl-exposed) Helicobacter retained viability even upon extracellular addition of the inactive versions of catalase, in contrast to cells receiving HOCl alone. The importance of the methionine-mediated quenching to the pathogen residing in the oxidant-rich gastric mucus was studied. In contrast to a catalase-null strain, both site-change mutants proficiently colonized the murine gastric mucosa, suggesting that the amino acid composition-dependent oxidant-quenching role of catalase is more important than the well described H2O2-dissipating catalytic role. Over 100 years after the discovery of catalase, these findings reveal a new non-enzymatic protective mechanism of action for the ubiquitous enzyme.
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Affiliation(s)
- Stéphane L Benoit
- From the Department of Microbiology, University of Georgia, Athens, Georgia 30602
| | - Robert J Maier
- From the Department of Microbiology, University of Georgia, Athens, Georgia 30602
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15
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Yu SC, Fen SY, Chien CL, Wong HC. Protective roles of katG-homologous genes against extrinsic peroxides in Vibrio parahaemolyticus. FEMS Microbiol Lett 2016; 363:fnw038. [PMID: 26892020 DOI: 10.1093/femsle/fnw038] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/14/2016] [Indexed: 12/12/2022] Open
Abstract
The marine foodborne enteropathogen, Vibrio parahaemolyticus, has four putative catalase genes. Function of the katG-homologous genes, katG1(VPA0768) and katG2(VPA0453), was examined using gene deletion mutants, and compared with those of the katE-homologous genes, katE1(VPA1418) and katE2(VPA0305). Bacterial growth of ΔkatG1 was significantly delayed in the presence of 200-300 μM H2O2, and such inhibition was enhanced when incubation temperature was lowered from 37°C to 22°C. In the stationary phase, the ΔkatG1 strain was more susceptible to the lethal dosage of H2O2 than the ΔkatE1 strain. The minimum inhibitory concentrations and minimum bactericidal concentrations revealed that ΔkatE1/ΔkatE2 strains were more susceptible to H2O2 than the ΔkatG1/ΔkatG2 strains in exponential phase, while ΔkatG1 was more susceptible than the ΔkatE1/ΔkatE2 strains in the starved culture. This study demonstrated the chief antioxidative role of katG1 in the stationary phase and starved culture of V. parahaemolyticus, while katG1 and katG2 were also responsive to H2O2 and cumene hydroperoxide in the exponential phase.
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Affiliation(s)
- Shu-Chuan Yu
- Department of Microbiology, Soochow University, Taipei, Taiwan 111, Republic of China
| | - Shin-yuan Fen
- Department of Microbiology, Soochow University, Taipei, Taiwan 111, Republic of China
| | - Cheng-Lun Chien
- Department of Microbiology, Soochow University, Taipei, Taiwan 111, Republic of China
| | - Hin-chung Wong
- Department of Microbiology, Soochow University, Taipei, Taiwan 111, Republic of China
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16
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Fu H, Yuan J, Gao H. Microbial oxidative stress response: Novel insights from environmental facultative anaerobic bacteria. Arch Biochem Biophys 2015; 584:28-35. [DOI: 10.1016/j.abb.2015.08.012] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 08/19/2015] [Accepted: 08/20/2015] [Indexed: 02/03/2023]
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17
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Gholami M, Etemadifar Z, Bouzari M. Isolation a new strain of Kocuria rosea capable of tolerating extreme conditions. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2015; 144:113-119. [PMID: 25839781 DOI: 10.1016/j.jenvrad.2015.03.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2012] [Revised: 01/01/2015] [Accepted: 03/10/2015] [Indexed: 06/04/2023]
Abstract
A new actinobacterial strain was isolated from Ab-e-Siah spring (dark water) taken from the Ramsar city in Iran, and subjected to several stress conditions investigation. The isolate, named MG2 strain, was Gram-positive, aerobic, diplococci or tetrad shaped, non-spore forming and non-motile. Phylogenetic analysis of the isolate using 16S rDNA sequence indicated that the organism matched best with the genus Kocuria and the highest sequence similarities (98.55%) being found with Kocuria rosea. The 16S rDNA sequence determined in this study has been deposited in the NCBI database with the accession no. JX534199, K. rosea strain MG2. The isolated strain was an alkaliphilic-mesophilic bacterium because the optimal growth was observed at pH 9.2 and temperature of 28 °C under aerobic condition. MG2 was a halotolerant strain and tolerated maximally to 15% NaCl concentraion. Viability analysis by flow cytometry indicated that this strain had highly resistance to UV-C radiation and moderately resistance to desiccation after 28 days. The viability of K. rosea strains MG2 and Deinococcus radiodurans R1 were determined D87 and D98 according to D index, respectively, by a dose radiation 25 J/cm (Appukuttan et al., 2006). Thus the UV resistance of strain MG2 was comparable with representative radiation resistant Deinococcus. Also MG2 was grown at 1-4% of H2O2 as an oxidant agent. This research is the first study on multiple extreme resistance of Kocuria rosea new strain (MG2) isolated in Iran.
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Affiliation(s)
- M Gholami
- Department of Biology, Faculty of Sciences, University of Isfahan, Hezarjarib St., Azadi Sq., 81746-73441, Isfahan, Iran
| | - Z Etemadifar
- Department of Biology, Faculty of Sciences, University of Isfahan, Hezarjarib St., Azadi Sq., 81746-73441, Isfahan, Iran.
| | - M Bouzari
- Department of Biology, Faculty of Sciences, University of Isfahan, Hezarjarib St., Azadi Sq., 81746-73441, Isfahan, Iran
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18
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Li N, Luo Q, Jiang Y, Wu G, Gao H. Managing oxidative stresses in Shewanella oneidensis: intertwined roles of the OxyR and OhrR regulons. Environ Microbiol 2014; 16:1821-34. [PMID: 25009841 DOI: 10.1111/1462-2920.12418] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Shewanella oneidensis, renowned for its remarkable respiratory abilities, inhabit redox-stratified environments prone to reactive oxygen species (ROS)formation. Two major oxidative stress regulators,analogues of OxyR and OhrR, specifically respond to H(2)O(2) and organic peroxides (OP), respectively, are encoded in the genome based on sequence comparison to well-studied models. Presumably, these analogues provide protection from ROS. An understanding of S. oneidensis OxyR has been established recently, which functions as both repressor and activator to mediate H(2)O(2)-induced oxidative stress. Here,we report the first study of elucidating molecular mechanisms underlying the S. oneidensis response to OP-induced oxidative stress. We show tha tS. oneidensis has OhrR, an OP stress regulator with two novel features. The sensing and responding residues of OhrR are not equally important for regulation and the regulator directly controls transcription of the SO1563 gene, in addition to the ohr gene which encodes the major OP scavenging protein. Importantly,we present evidence suggesting that the OxyR and OhrR regulons of S. oneidensis appear to be functionally intertwined as both OxyR and OhrR systems can sense and response to H(2)O(2) and OP agents.
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19
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Ayala G, Escobedo-Hinojosa WI, Cruz-Herrera CFDL, Romero I. Exploring alternative treatments for Helicobacter pylori infection. World J Gastroenterol 2014; 20:1450-1469. [PMID: 24587621 PMCID: PMC3925854 DOI: 10.3748/wjg.v20.i6.1450] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Revised: 12/21/2013] [Accepted: 01/05/2014] [Indexed: 02/06/2023] Open
Abstract
Helicobacter pylori (H. pylori) is a successful pathogen that can persist in the stomach of an infected person for their entire life. It provokes chronic gastric inflammation that leads to the development of serious gastric diseases such as peptic ulcers, gastric cancer and Mucosa associated lymphoid tissue lymphoma. It is known that these ailments can be avoided if the infection by the bacteria can be prevented or eradicated. Currently, numerous antibiotic-based therapies are available. However, these therapies have several inherent problems, including the appearance of resistance to the antibiotics used and associated adverse effects, the risk of re-infection and the high cost of antibiotic therapy. The delay in developing a vaccine to prevent or eradicate the infection has furthered research into new therapeutic approaches. This review summarises the most relevant recent studies on vaccine development and new treatments using natural resources such as plants, probiotics and nutraceuticals. In addition, novel alternatives based on microorganisms, peptides, polysaccharides, and intragastric violet light irradiation are presented. Alternative therapies have not been effective in eradicating the bacteria but have been shown to maintain low bacterial levels. Nevertheless, some of them are useful in preventing the adverse effects of antibiotics, modulating the immune response, gastroprotection, and the general promotion of health. Therefore, those agents can be used as adjuvants of allopathic anti-H. pylori eradication therapy.
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20
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Abstract
The thioredoxin (Trx) system, which is composed of NADPH, thioredoxin reductase (TrxR), and thioredoxin, is a key antioxidant system in defense against oxidative stress through its disulfide reductase activity regulating protein dithiol/disulfide balance. The Trx system provides the electrons to thiol-dependent peroxidases (peroxiredoxins) to remove reactive oxygen and nitrogen species with a fast reaction rate. Trx antioxidant functions are also shown by involvement in DNA and protein repair by reducing ribonucleotide reductase, methionine sulfoxide reductases, and regulating the activity of many redox-sensitive transcription factors. Moreover, Trx systems play critical roles in the immune response, virus infection, and cell death via interaction with thioredoxin-interacting protein. In mammalian cells, the cytosolic and mitochondrial Trx systems, in which TrxRs are high molecular weight selenoenzymes, together with the glutathione-glutaredoxin (Grx) system (NADPH, glutathione reductase, GSH, and Grx) control the cellular redox environment. Recently mammalian thioredoxin and glutathione systems have been found to be able to provide the electrons crossly and to serve as a backup system for each other. In contrast, bacteria TrxRs are low molecular weight enzymes with a structure and reaction mechanism distinct from mammalian TrxR. Many bacterial species possess specific thiol-dependent antioxidant systems, and the significance of the Trx system in the defense against oxidative stress is different. Particularly, the absence of a GSH-Grx system in some pathogenic bacteria such as Helicobacter pylori, Mycobacterium tuberculosis, and Staphylococcus aureus makes the bacterial Trx system essential for survival under oxidative stress. This provides an opportunity to kill these bacteria by targeting the TrxR-Trx system.
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Affiliation(s)
- Jun Lu
- Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
| | - Arne Holmgren
- Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
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21
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Kuhns LG, Mahawar M, Sharp JS, Benoit S, Maier RJ. Role of Helicobacter pylori methionine sulfoxide reductase in urease maturation. Biochem J 2013; 450:141-8. [PMID: 23181726 PMCID: PMC3935233 DOI: 10.1042/bj20121434] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The persistence of the gastric pathogen Helicobacter pylori is due in part to urease and Msr (methionine sulfoxide reductase). Upon exposure to relatively mild (21% partial pressure of O2) oxidative stress, a Δmsr mutant showed both decreased urease specific activity in cell-free extracts and decreased nickel associated with the partially purified urease fraction as compared with the parent strain, yet urease apoprotein levels were the same for the Δmsr and wild-type extracts. Urease activity of the Δmsr mutant was not significantly different from the wild-type upon non-stress microaerobic incubation of strains. Urease maturation occurs through nickel mobilization via a suite of known accessory proteins, one being the GTPase UreG. Treatment of UreG with H2O2 resulted in oxidation of MS-identified methionine residues and loss of up to 70% of its GTPase activity. Incubation of pure H2O2-treated UreG with Msr led to reductive repair of nine methionine residues and recovery of up to full enzyme activity. Binding of Msr to both oxidized and non-oxidized UreG was observed by cross-linking. Therefore we conclude Msr aids the survival of H. pylori in part by ensuring continual UreG-mediated urease maturation under stress conditions.
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Affiliation(s)
- Lisa G. Kuhns
- Department of Microbiology, University of Georgia, Athens, GA 30602, U.S.A
| | - Manish Mahawar
- Department of Microbiology, University of Georgia, Athens, GA 30602, U.S.A
| | - Joshua S. Sharp
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, U.S.A
| | - Stéphane Benoit
- Department of Microbiology, University of Georgia, Athens, GA 30602, U.S.A
| | - Robert J. Maier
- Department of Microbiology, University of Georgia, Athens, GA 30602, U.S.A
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Abstract
The transition metal nickel (Ni) is critical for the pathogenicity of Helicobacter pylori. Indeed the element is a required component of two enzymes, hydrogenase and urease, that have been shown to be important for in vivo colonization of the host gastric mucosa. Urease accounts for up to 10% of the total cellular H. pylori protein content, and therefore the bacterial Ni demand is very high. H. pylori possess two small and abundant histidine-rich, Ni-binding proteins, Hpn and Hpn-like, whose physiological role in the host have not been investigated. In this study, special husbandry conditions were used to control Ni levels in the host (mouse), including the use of Ni-free versus Ni-supplemented food. The efficacy of each diet was confirmed by measuring the Ni concentrations in sera of mice fed with either diet. Colonization levels (based on rank tests) of the Δhpn Δhpn-like double mutants isolated from the mice provided Ni-deficient chow were statistically lower than those for mice given Ni in their diet. In contrast, H. pylori wild-type colonization levels were similar in both host groups (e.g., regardless of Ni levels). Our results indicate that the gastric pathogen H. pylori can utilize stored Ni via defined histidine-rich proteins to aid colonization of the host.
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Mehmood K, Hasan F. Construction and use of a prokaryotic expression system for Helicobacter pylori AhpC. BMC Res Notes 2012; 5:328. [PMID: 22731891 PMCID: PMC3439327 DOI: 10.1186/1756-0500-5-328] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Accepted: 06/21/2012] [Indexed: 02/06/2023] Open
Abstract
Background Helicobacter pylori is an important pathogen responsible for human gastric problems like inflammation, ulcers and cancer. It is widely prevalent in developing countries with low socioeconomic status. Since the infection remains asymptomatic in most individuals, efforts for efficient diagnostic markers to identify high risk patients are warranted. In this study, we constructed an expression vector that overexpresses the H. pylori AhpC protein as a glutathione S-transferase fusion protein. We furthermore examined whether this recombinant fusion protein retained immunogenicity and thus would be useful as a diagnostic marker. Findings The full-length tsaA gene from H. pylori strain G27, which encodes AhpC, was cloned in plasmid vector pGEX-6P-2 to create the recombinant plasmid vector pGEX-tsaA. The nucleotide sequence of the clone showed 100% homology with corresponding published sequence of original gene. Over-expression of the target protein GST-AhpC was achieved in E. coli BL21 (DE3) cells by induction with isopropyl-beta-D-thiogalactoside (IPTG). GST-AhpC was extracted and identified using SDS-PAGE as a 52 kDa protein. Western blotting results using commercial antibodies against whole cell H. pylori showed that the fusion protein retained immunogenecity. Conclusion A recombinant prokaryotic expression system was successfully established with high expression efficiency for target fusion gene pGEX-tsaA. The expressed GST-AhpC protein showed immunoreactivity against commercial anti-H. pylori antibodies. This recombinant fusion protein can be developed as a diagnostic marker for screening patients with chronic H. pylori infections.
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Affiliation(s)
- Khalid Mehmood
- Department of Microbiology, Quaid-i-Azam University, Islamabad, 45320, Pakistan.
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24
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Alkyl hydroperoxide reductase is required for Helicobacter cinaedi intestinal colonization and survival under oxidative stress in BALB/c and BALB/c interleukin-10-/- mice. Infect Immun 2011; 80:921-8. [PMID: 22184416 DOI: 10.1128/iai.05477-11] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Helicobacter cinaedi, a common human intestinal bacterium, has been implicated in various enteric and systemic diseases in normal and immunocompromised patients. Protection against oxidative stress is a crucial component of bacterium-host interactions. Alkyl hydroperoxide reductase C (AhpC) is an enzyme responsible for detoxification of peroxides and is important in protection from peroxide-induced stress. H. cinaedi possesses a single ahpC, which was investigated with respect to its role in bacterial survival during oxidative stress. The H. cinaedi ahpC mutant had diminished resistance to organic hydroperoxide toxicity but increased hydrogen peroxide resistance compared with the wild-type (WT) strain. The mutant also exhibited an oxygen-sensitive phenotype and was more susceptible to killing by macrophages than the WT strain. In vivo experiments in BALB/c and BALB/c interleukin-10 (IL-10)(-/-) mice revealed that the cecal colonizing ability of the ahpC mutant was significantly reduced. The mutant also had diminished ability to induce bacterium-specific immune responses in vivo, as shown by immunoglobulin (IgG2a and IgG1) serum levels. Collectively, these data suggest that H. cinaedi ahpC not only contributes to protecting the organism against oxidative stress but also alters its pathogenic properties in vivo.
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25
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Mahawar M, Tran V, Sharp JS, Maier RJ. Synergistic roles of Helicobacter pylori methionine sulfoxide reductase and GroEL in repairing oxidant-damaged catalase. J Biol Chem 2011; 286:19159-69. [PMID: 21460217 DOI: 10.1074/jbc.m111.223677] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Hypochlorous acid (HOCl) produced via the enzyme myeloperoxidase is a major antibacterial oxidant produced by neutrophils, and Met residues are considered primary amino acid targets of HOCl damage via conversion to Met sulfoxide. Met sulfoxide can be repaired back to Met by methionine sulfoxide reductase (Msr). Catalase is an important antioxidant enzyme; we show it constitutes 4-5% of the total Helicobacter pylori protein levels. msr and katA strains were about 14- and 4-fold, respectively, more susceptible than the parent to killing by the neutrophil cell line HL-60 cells. Catalase activity of an msr strain was much more reduced by HOCl exposure than for the parental strain. Treatment of pure catalase with HOCl caused oxidation of specific MS-identified Met residues, as well as structural changes and activity loss depending on the oxidant dose. Treatment of catalase with HOCl at a level to limit structural perturbation (at a catalase/HOCl molar ratio of 1:60) resulted in oxidation of six identified Met residues. Msr repaired these residues in an in vitro reconstituted system, but no enzyme activity could be recovered. However, addition of GroEL to the Msr repair mixture significantly enhanced catalase activity recovery. Neutrophils produce large amounts of HOCl at inflammation sites, and bacterial catalase may be a prime target of the host inflammatory response; at high concentrations of HOCl (1:100), we observed loss of catalase secondary structure, oligomerization, and carbonylation. The same HOCl-sensitive Met residue oxidation targets in catalase were detected using chloramine-T as a milder oxidant.
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Affiliation(s)
- Manish Mahawar
- Department of Microbiology, University of Georgia, Athens, Georgia 30602, USA
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26
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Lechardeur D, Fernandez A, Robert B, Gaudu P, Trieu-Cuot P, Lamberet G, Gruss A. The 2-Cys peroxiredoxin alkyl hydroperoxide reductase c binds heme and participates in its intracellular availability in Streptococcus agalactiae. J Biol Chem 2010; 285:16032-41. [PMID: 20332091 PMCID: PMC2871472 DOI: 10.1074/jbc.m109.024505] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2009] [Revised: 03/12/2010] [Indexed: 11/06/2022] Open
Abstract
Heme is a redox-reactive molecule with vital and complex roles in bacterial metabolism, survival, and virulence. However, few intracellular heme partners were identified to date and are not well conserved in bacteria. The opportunistic pathogen Streptococcus agalactiae (group B Streptococcus) is a heme auxotroph, which acquires exogenous heme to activate an aerobic respiratory chain. We identified the alkyl hydroperoxide reductase AhpC, a member of the highly conserved thiol-dependent 2-Cys peroxiredoxins, as a heme-binding protein. AhpC binds hemin with a K(d) of 0.5 microm and a 1:1 stoichiometry. Mutagenesis of cysteines revealed that hemin binding is dissociable from catalytic activity and multimerization. AhpC reductase activity was unchanged upon interaction with heme in vitro and in vivo. A group B Streptococcus ahpC mutant displayed attenuation of two heme-dependent functions, respiration and activity of a heterologous catalase, suggesting a role for AhpC in heme intracellular fate. In support of this hypothesis, AhpC-bound hemin was protected from chemical degradation in vitro. Our results reveal for the first time a role for AhpC as a heme-binding protein.
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Affiliation(s)
- Delphine Lechardeur
- From the Institut National de la Recherche Agronomique, Institut Micalis, UMR 1319, 78352 Jouy-en-Josas
| | - Annabelle Fernandez
- From the Institut National de la Recherche Agronomique, Institut Micalis, UMR 1319, 78352 Jouy-en-Josas
| | - Bruno Robert
- the Commissariat à l'Energie Atomique, Institut de Biologie et de Technologie de Saclay, CNRS, URA 2096, 91400 Gif sur Yvette, and
| | - Philippe Gaudu
- From the Institut National de la Recherche Agronomique, Institut Micalis, UMR 1319, 78352 Jouy-en-Josas
| | - Patrick Trieu-Cuot
- the Institut Pasteur, Unité de Biologie des Bactéries Pathogènes à Gram-Positif, CNRS, URA 2172, 75015 Paris, France
| | - Gilles Lamberet
- From the Institut National de la Recherche Agronomique, Institut Micalis, UMR 1319, 78352 Jouy-en-Josas
| | - Alexandra Gruss
- From the Institut National de la Recherche Agronomique, Institut Micalis, UMR 1319, 78352 Jouy-en-Josas
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27
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Noyan T, Guducuoglu H, Ilhan M. A study of oxidative stress parameters in anti-helicobacter pylorus immunoglobulin g positive and negative gastric cancer patients. Yonsei Med J 2009; 50:677-82. [PMID: 19881972 PMCID: PMC2768243 DOI: 10.3349/ymj.2009.50.5.677] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2007] [Revised: 11/20/2007] [Accepted: 11/20/2007] [Indexed: 12/19/2022] Open
Abstract
PURPOSE Helicobacter pylorus (HP) is a Gram-negative spiral-shaped microaerophilic bacterium, which colonizes in the gastric mucosa of humans. The gastric human pathogen HP causes chronic gastritis and ulcers, and has a strong relationship with gastric cancer. The aim of this study was to determine advanced oxidation protein products (AOPP) levels, activities of myeloperoxidase (MPO) and catalase (CAT) in two groups. MATERIALS AND METHODS For this aim, one group included 30 patients with gastric cancer (Group 1) and the other included 30 subjects with non-gastric cancer and Anti-HP immunoglobulin (Ig) G antibody positive (group 2). Anti-HP IgG antibody test values were found as positive in fifty percent of group 1 and all of the group 2 patients. RESULTS Significantly increased AOOP levels were found in group 1 (p < 0.05) compared to group 2. There were no significant differences between the groups in regard to activities of MPO and CAT. In addition, AOPP level, MPO and CAT activities were similar among the Anti-HP IgG positive and negative subgroups of group 1 patients. CONCLUSION The result of this study indicated that gastric cancer patients were characterized by increased protein oxidation, whereas there was no significant difference in oxidative stress parameters and antioxidant enzyme activity between the Anti-HP IgG positive and negative gastric cancer patients.
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Affiliation(s)
- Tevfik Noyan
- Department of Biochemistry, Yuzuncu Yil University, Medical Faculty, Van, Turkey.
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28
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Wang G, Conover RC, Olczak AA, Alamuri P, Johnson MK, Maier RJ. Oxidative stress defense mechanisms to counter iron-promoted DNA damage inHelicobacter pylori. Free Radic Res 2009; 39:1183-91. [PMID: 16298744 DOI: 10.1080/10715760500194018] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Iron, a key element in Fenton chemistry, causes oxygen-related toxicity to cells of most living organisms. Helicobacter pylori is a microaerophilic bacterium that infects human gastric mucosa and causes a series of gastric diseases. Exposure of H. pylori cells to air for 2 h elevated the level of free iron by about 4-fold as measured by electron paramagnetic resonance spectroscopy. H. pylori cells accumulated more free iron as they approached stationary phase growth, and they concomitantly suffered more DNA damage as indicated by DNA fragmentation analysis. Relationships between the intracellular free iron level, specific oxidative stress enzymes, and DNA damage were identified, and new roles for three oxidative stress-combating enzymes in H. pylori are proposed. Mutant cells defective in either catalase (KatA), in superoxide dismutase (SodB) or in alkyl hydroperoxide reductase (AhpC) were more sensitive to oxidative stress conditions; and they accumulated more free (toxic) iron; and they suffered more DNA fragmentation compared to wild type cells. A significant proportion of cells of sodB, ahpC, or katA mutant strains developed into the stress-induced coccoid form or lysed; they also contained significantly higher amounts of 8-oxo-guanine associated with their DNA, compared to wild type cells.
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Affiliation(s)
- Ge Wang
- Department of Microbiology, University of Georgia, Athens, 30602, USA
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29
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Huang ZG, Duan GC, Fan QT, Zhang WD, Song CH, Huang XY, Zhang RG. Mutation of cytotoxin-associated gene A affects expressions of antioxidant proteins of Helicobacter pylori. World J Gastroenterol 2009; 15:599-606. [PMID: 19195063 PMCID: PMC2653352 DOI: 10.3748/wjg.15.599] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To determine if disruption of the cagA gene of Helicobacter pylori (H pylori) has an effect on the expression of other proteins at proteome level.
METHODS: Construction of a cagA knock out mutant Hp27_ΔcagA (cagA-) via homologous recombination with the wild-type strain Hp27 (cagA+) as a recipient was performed. The method of sonication-urea-CHAPS-DTT was employed to extract bacterial proteins from both strains. Soluble proteins were analyzed by two-dimensional electrophoresis (2-DE). Images of 2-DE gels were digitalized and analyzed. Only spots that had a statistical significance in differential expression were selected and analyzed by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS). Biological information was used to search protein database and identify the biological function of proteins.
RESULTS: The proteome expressions between wild-type strain and isogenic mutant with the cagA gene knocked-out were compared. Five protein spots with high abundance in bacteria proteins of wild-type strains, down-regulated or absently expressed in bacteria proteins of mutants, were identified and analyzed. From a quantitative point of view, the identified proteins are related to the cagA gene and important antioxidant proteins of H pylori, including alkyl hydroperoxide reductase (Ahp), superoxide dismutase (SOD) and modulator of drug activity (Mda66), respectively, suggesting that cagA is important to maintain the normal activity of antioxidative stress and ensure H pylori persistent colonization in the host.
CONCLUSION: cagA gene is relevant to the expressions of antioxidant proteins of H pylori, which may be a novel mechanism involved in H pylori cagA pathogenesis.
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30
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Mohammadian T, Doosti M, Paknejad M, Siavoshi F, Massarrat S, Soukhtanloo M. Production of polyclonal antibody against alkyl hydroperoxide reductase of Helicobacter pylori and its antigenicity. Hybridoma (Larchmt) 2009; 27:481-5. [PMID: 19108621 DOI: 10.1089/hyb.2008.0054] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Stool-antigen detection kits for diagnosis of Helicobacter pylori infection have been widely used because of their full non-invasive nature. Because Helicobacter pylori strains show a distinctive genetic diversity, it is important to find a protein that is a common antigen of various strains and shows a strong immunogenicity for the development of a stool- antigen detection kit. Alkyl hydroperoxide reductase (AhpC) of Helicobacter pylori strongly reacts with the sera of patients with gastritis and peptic ulcer. Therefore, AhpC seems to be an excellent candidate as a target protein for this study. Accordingly, polyclonal antiserum against AhpC was produced in adult New Zealand white rabbits by using AhpC in the gel bands without adding Freund's adjuvant. In addition, isolation and purification of AhpC were perfomed by preparative sodium dodecyl sulfate polyacrylamide gel electrophoresis and electroelution. In this study, a simple method was used for rapid production of polyclonal antibody against AhpC of H. pylori, which avoids both the long-term AhpC purification and the addition of Freund's adjuvant. One-dimensional preparative gel electrophoresis allows a single and short purification step; the high-resolution capacity of this technique leads to a high level of purity of the protein and consequently to a very high specificity of the antibody. Moreover, this method avoids contamination by other non-specific proteins, which often appear during the purification process by column chromatographic techniques, which may also decrease the purity of the immunogen. The present method is simple, rapid and cost-effective, and also makes it possible to produce antibody for stool-antigen enzyme immunoassay in a short time and at low cost.
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Affiliation(s)
- Taher Mohammadian
- Department of Microbiology, Faculty of Basic Sciences, Islamic Azad University, Shahryar-Shahr-e-qods-Branch, Qods City, Iran
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31
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Blackman LM, Hardham AR. Regulation of catalase activity and gene expression during Phytophthora nicotianae development and infection of tobacco. MOLECULAR PLANT PATHOLOGY 2008; 9:495-510. [PMID: 18705863 PMCID: PMC6640254 DOI: 10.1111/j.1364-3703.2008.00478.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Plant defence against pathogen attack typically incorporates an oxidative burst involving elevated levels of reactive oxygen species such as hydrogen peroxide. In the present study, we have used an in-gel assay to monitor the activity of the hydrogen peroxide scavenging enzyme, catalase, during asexual development of Phytophthora nicotianae and during infection of host tobacco plants. In vitro, catalase activity is highest in sporulating hyphae; in planta, catalase activity increases dramatically about 8 h after host inoculation. We have cloned and characterized three catalase genes, designated PnCat1, PnCat2 and PnCat3, from P. nicotianae and identified their homologues in P. infestans, P. sojae and P. ramorum. In all three species, Cat2 is predicted to be targeted to the peroxisome and the other catalases are likely to be cytosolic. Quantitative real-time PCR assessment of catalase transcripts during development and infection indicates that peroxisomal PnCat2 is the gene predominantly expressed, with transcript levels peaking in vitro in sporulating hyphae and in planta increasing dramatically during the first 24 h after inoculation of susceptible tobacco seedlings. Levels of tobacco catalase gene expression are significantly down-regulated in susceptible tobacco 4, 8 and 24 h post-inoculation and in resistant plants at 24 h post-inoculation. Together, our results give evidence that during infection P. nicotianae increases its own peroxisomal catalase levels while concurrently down-regulating host catalase expression. This behaviour is consistent with a role of pathogen catalase in counterdefence and protection against oxidative stress and of pathogen-orchestrated enhanced plant cell death to support necrotrophic pathogen growth and plant colonization.
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Affiliation(s)
- Leila M Blackman
- Plant Cell Biology Group, Research School of Biological Sciences, Australian National University, Canberra, ACT 2601, Australia
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32
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The Campylobacter jejuni thiol peroxidases Tpx and Bcp both contribute to aerotolerance and peroxide-mediated stress resistance but have distinct substrate specificities. J Bacteriol 2008; 190:5279-90. [PMID: 18515414 DOI: 10.1128/jb.00100-08] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The microaerophilic food-borne pathogen Campylobacter jejuni experiences variable oxygen concentrations during its life cycle, especially during transitions between the external environment and the avian or mammalian gut. Single knockout mutations in either one of two related thiol peroxidase genes, tpx and bcp, resulted in normal microaerobic growth (10% [vol/vol] oxygen) but poorer growth than that of the wild type under high-aeration conditions (21% [vol/vol] oxygen). However, a tpx/bcp double mutant had a severe microaerobic growth defect and did not grow at high aeration in shake flasks. Although the single mutant strains were no more sensitive than the wild-type strains in disc diffusion assays with hydrogen peroxide, organic peroxides, superoxide, or nitrosative stress agents, in all cases the double mutant was hypersensitive. Quantitative cell viability and cellular lipid peroxidation assays indicated some increased sensitivity of the single tpx and bcp mutants to peroxide stress. Protein carbonylation studies revealed that the tpx/bcp double mutant had a higher degree of oxygen- and peroxide-induced oxidative protein damage than did either of the single mutants. An analysis of the peroxidase activity of the purified recombinant enzymes showed that, surprisingly, Tpx reduced only hydrogen peroxide as substrate, whereas Bcp also reduced organic peroxides. Immunoblotting of wild-type cell extracts with Tpx- or Bcp-specific antibodies showed increased abundance of both proteins under high aeration compared to that under microaerobic growth conditions. Taken together, the results suggest that Tpx and Bcp are partially redundant antioxidant enzymes that play an important role in protection of C. jejuni against oxygen-induced oxidative stress.
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33
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Abstract
Peroxiredoxins constitute an important component of the bacterial defense against toxic peroxides. These enzymes use reactive cysteine thiols to reduce peroxides with electrons ultimately derived from reduced pyridine dinucleotides. Studies examining the regulation and physiological roles of AhpC, Tpx, Ohr and OsmC reveal the multilayered nature of bacterial peroxide defense. AhpC is localized in the cytoplasm and has a wide substrate range that includes H2O2, organic peroxides and peroxynitrite. This enzyme functions in both the control of endogenous peroxides, as well as in the inducible defense response to exogenous peroxides or general stresses. Ohr, OsmC and Tpx are organic peroxide specific. Tpx is localized to the periplasm and can be involved in either constitutive peroxide defense or participate in oxidative stress inducible responses depending on the organism. Ohr is an organic peroxide specific defense system that is under the control of the organic peroxide sensing repressor OhrR. In some organisms Ohr homologs are regulated in response to general stress. Clear evidence indicates that AhpC, Tpx and Ohr are involved in virulence. The role of OsmC is less clear. Regulation of OsmC expression is not oxidative stress inducible, but is controlled by multiple general stress responsive regulators.
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Affiliation(s)
- James M Dubbs
- Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand
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34
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Ge R, Sun X, Gu Q, Watt RM, Tanner JA, Wong BCY, Xia HH, Huang JD, He QY, Sun H. A proteomic approach for the identification of bismuth-binding proteins in Helicobacter pylori. J Biol Inorg Chem 2007; 12:831-42. [PMID: 17503094 DOI: 10.1007/s00775-007-0237-7] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2007] [Accepted: 04/02/2007] [Indexed: 02/07/2023]
Abstract
Helicobacter pylori is a major human pathogen that can cause peptic ulcers and chronic gastritis. Bismuth-based triple or quadruple therapies are commonly recommended for the treatment of H. pylori infections. However, the molecular mechanisms underlying treatment with bismuth are currently not fully understood. We have conducted a detailed comparative proteomic analysis of H. pylori cells both before and after treatment with colloidal bismuth subcitrate (CBS). Eight proteins were found to be significantly upregulated or downregulated in the presence of CBS (20 microg mL(-1)). Bismuth-induced oxidative stress was confirmed by detecting higher levels of lipid hydroperoxide (approximately 1.8 times) and hemin (approximately 3.4 times), in whole cell extracts of bismuth-treated H. pylori cells, compared with those from untreated cells. The presence of bismuth also led to an approximately eightfold decrease in cellular protease activities. Using immobilized-bismuth affinity chromatography, we isolated and subsequently identified seven bismuth-binding proteins from H. pylori cell extracts. The intracellular levels of four of these proteins (HspA, HspB, NapA and TsaA) were influenced by the addition of CBS, which strongly suggests that they interact directly with bismuth. The other bismuth-interacting proteins identified were two enzymes (fumarase and the urease subunit UreB), and a translational factor (Ef-Tu). Our data suggest that the inhibition of proteases, modulation of cellular oxidative stress and interference with nickel homeostasis may be key processes underlying the molecular mechanism of bismuth's actions against H. pylori.
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Affiliation(s)
- Ruiguang Ge
- Department of Chemistry and Open Laboratory of Chemical Biology, The University of Hong Kong, Pokfulam Road, Hong Kong, People's Republic of China
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35
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Kaakoush NO, Kovach Z, Mendz GL. Potential role of thiol:disulfide oxidoreductases in the pathogenesis ofHelicobacter pylori. ACTA ACUST UNITED AC 2007; 50:177-83. [PMID: 17521354 DOI: 10.1111/j.1574-695x.2007.00259.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Helicobacter pylori infections are responsible for a sequence of molecular events which ultimately result in the development of gastric diseases. The pathogenesis of H. pylori has been studied extensively with strong focus on the identification of virulence factors. In contrast, the involvement of thiol:disulfide oxidoreductases in bacterial pathogenesis is less well understood. This paper provides a review of the current knowledge of H. pylori putative thiol:disulfide oxidoreductases, and their potential role in promoting virulence and colonization. Several bioinformatic analyses served to complete the information on these oxidoreductases of H. pylori.
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Affiliation(s)
- Nadeem O Kaakoush
- School of Medical Sciences, The University of New South Wales, Sydney, Australia
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36
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Belzer C, Stoof J, van Vliet AHM. Metal-responsive gene regulation and metal transport in Helicobacter species. Biometals 2007; 20:417-29. [PMID: 17294126 PMCID: PMC2798029 DOI: 10.1007/s10534-006-9028-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2006] [Accepted: 07/20/2006] [Indexed: 12/13/2022]
Abstract
Helicobacter species are among the most successful colonizers of the mammalian gastrointestinal and hepatobiliary tract. Colonization is usually lifelong, indicating that Helicobacter species have evolved intricate mechanisms of dealing with stresses encountered during colonization of host tissues, like restriction of essential metal ions. The recent availability of genome sequences of the human gastric pathogen Helicobacter pylori, the murine enterohepatic pathogen Helicobacter hepaticus and the unannotated genome sequence of the ferret gastric pathogen Helicobacter mustelae has allowed for comparative genome analyses. In this review we present such analyses for metal transporters, metal-storage and metal-responsive regulators in these three Helicobacter species, and discuss possible contributions of the differences in metal metabolism in adaptation to the gastric or enterohepatic niches occupied by Helicobacter species.
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Affiliation(s)
- Clara Belzer
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Room L-455, ’s Gravendijkwal 230, 3015CE Rotterdam, The Netherlands
| | - Jeroen Stoof
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Room L-455, ’s Gravendijkwal 230, 3015CE Rotterdam, The Netherlands
| | - Arnoud H. M. van Vliet
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Room L-455, ’s Gravendijkwal 230, 3015CE Rotterdam, The Netherlands
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37
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Hong Y, Wang G, Maier RJ. A Helicobacter hepaticus catalase mutant is hypersensitive to oxidative stress and suffers increased DNA damage. J Med Microbiol 2007; 56:557-562. [PMID: 17374900 PMCID: PMC2366902 DOI: 10.1099/jmm.0.46891-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Catalase (KatA) is known to play an important role in oxidative stress resistance in many bacterial species and a homologue exists in Helicobacter hepaticus, a member of the enterohepatic Helicobacter species. Here, a katA mutant was constructed by insertional mutagenesis and its oxidative stress phenotype was investigated. Catalase activity was readily detected [196 units (mg protein crude cell extract)(-1)] in the wild-type, whereas the mutant strain was deficient in, but not devoid of, activity. In contrast, Helicobacter pylori katA strains lack detectable catalase activity and wild-type H. pylori generally contains higher specific activity than H. hepaticus. Wild-type H. hepaticus cells tolerated 6 % O2 for growth, whilst the katA mutant could not survive at this oxygen level. Even at the optimal O2 level, the growth of the H. hepaticus katA strain was severely inhibited, which is also in contrast to H. pylori katA strains. Wild-type H. hepaticus cells withstood exposure to 100 mM H(2)O(2) but the katA mutant cells were killed by the same treatment. Wild-type cells suffered no significant DNA damage by H(2)O(2) treatment (100 mM for 6 min), whilst the same treatment resulted in severe DNA fragmentation in the katA mutant. Thus H. hepaticus KatA plays an important role as an antioxidant protein.
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Affiliation(s)
- Yang Hong
- Department of Microbiology, University of Georgia, Athens, GA 30602, USA
| | - Ge Wang
- Department of Microbiology, University of Georgia, Athens, GA 30602, USA
| | - Robert J Maier
- Department of Microbiology, University of Georgia, Athens, GA 30602, USA
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38
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Mehta NS, Benoit SL, Mysore J, Maier RJ. In vitro and in vivo characterization of alkyl hydroperoxide reductase mutant strains of Helicobacter hepaticus. Biochim Biophys Acta Gen Subj 2006; 1770:257-65. [PMID: 17098365 DOI: 10.1016/j.bbagen.2006.09.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2006] [Revised: 09/20/2006] [Accepted: 09/25/2006] [Indexed: 11/24/2022]
Abstract
Mutant strains in the tsaA gene encoding alkyl hydroperoxide reductase were more sensitive to O(2) and to oxidizing agents (paraquat, cumene hydroperoxide and t-butylhydroperoxide) than the wild type, but were markedly more resistant to hydrogen peroxide. The mutant strains resistance phenotype could be attributed to a 4-fold and 3-fold increase in the catalase protein amount and activity, respectively compared to the parent strain. The wild type did not show an increase in catalase expression in response to sequential increases in O(2) exposure or to oxidative stress reagents, so an adaptive compensatory mutation has probably occurred in the mutants. In support of this, chromosomal complementation of tsaA mutants restored alkyl hydroperoxide reductase, but catalase was still up-expressed in all complemented strains. The katA promoter sequence was the same in all mutant strains and the wild type. Like its Helicobacter pylori counterpart strain, a H. hepaticus tsaA mutant contained more lipid hydroperoxides than the wild type strain. Hepatic tissue from mice inoculated with a tsaA mutant had lesions similar to those inoculated with the wild type, and included coagulative necrosis of hepatocytes. The liver and cecum colonizing abilities of the wild type and tsaA mutant were comparable. Up-expression of catalase in the tsaA mutants likely permits the bacterium to compensate (in colonization and virulence attributes) for the loss of an otherwise important oxidative stress-combating enzyme, alkyl hydroperoxide reductase. The use of erythromycin resistance insertion as a facile way to screen for gene-targeted mutants, and the chromosomal complementation of those mutants are new genetic procedures for studying H. hepaticus.
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Affiliation(s)
- Nalini S Mehta
- Department of Microbiology, University of Georgia, Athens, GA 30602, USA
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39
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Alamuri P, Maier RJ. Methionine sulfoxide reductase in Helicobacter pylori: interaction with methionine-rich proteins and stress-induced expression. J Bacteriol 2006; 188:5839-50. [PMID: 16885452 PMCID: PMC1540062 DOI: 10.1128/jb.00430-06] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The reductive repair of oxidized methionine residues performed by methionine sulfoxide reductase is important for the gastric pathogen Helicobacter pylori to maintain persistent stomach colonization. Methionine-containing proteins that are targeted for repair by Msr were identified from whole-cell extracts (after cells were exposed to O(2) stress) by using a coimmunoprecipitation approach. Proteins identified as Msr-interacting included catalase, GroEL, thioredoxin-1 (Trx1), and site-specific recombinase; with one exception (Trx1, the reductant for Msr) all these proteins have approximately twofold higher methionine (Met) content than other proteins. These Met-rich proteins were purified and were shown to individually form a cross-linked adduct with Msr. Catalase-specific activity in an msr strain was one-half that of the parent strain; this difference was only observed under oxidative stress conditions, and the activity was restored to nearly wild-type levels by adding Msr plus dithiothreitol to msr strain extracts. In agreement with the cross-linking study, pure Msr used Trx1 but not Trx2 as a reductant. Comparative structure modeling classified the H. pylori Msr in class II within the MsrB family, like the Neisseria enzymes. Pure H. pylori enzyme reduced only the R isomer of methyl p-tolyl-sulfoxide with an apparent K(m) of 4.1 mM for the substrate. Stress conditions (peroxide, peroxynitrite, and iron starvation) all caused approximately 3- to 3.5-fold transcriptional up-regulation of msr. Neither the O(2) level during growth nor the use of background regulatory mutants had a significant effect on msr transcription. Late log and stationary phase cultures had the highest Msr protein levels and specific activity.
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Affiliation(s)
- Praveen Alamuri
- Department of Microbiology, The University of Georgia, Biological Sciences Bldg., 527, 1000 Cedar Street, Athens, GA 30602, USA
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40
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Abstract
The gastric pathogen Helicobacter pylori induces a strong inflammatory host response, yet the bacterium maintains long-term persistence in the host. H. pylori combats oxidative stress via a battery of diverse activities, some of which are unique or newly described. In addition to using the well-studied bacterial oxidative stress resistance enzymes superoxide dismutase and catalase, H. pylori depends on a family of peroxiredoxins (alkylhydroperoxide reductase, bacterioferritin co-migratory protein and a thiol-peroxidase) that function to detoxify organic peroxides. Newly described antioxidant proteins include a soluble NADPH quinone reductase (MdaB) and an iron sequestering protein (NapA) that has dual roles - host inflammation stimulation and minimizing reactive oxygen species production within H. pylori. An H. pylori arginase attenuates host inflammation, a thioredoxin required as a reductant for many oxidative stress enzymes is also a chaperon, and some novel properties of KatA and AhpC were discovered. To repair oxidative DNA damage, H. pylori uses an endonuclease (Nth), DNA recombination pathways and a newly described type of bacterial MutS2 that specifically recognizes 8-oxoguanine. A methionine sulphoxide reductase (Msr) plays a role in reducing the overall oxidized protein content of the cell, although it specifically targets oxidized Met residues. H. pylori possess few stress regulator proteins, but the key roles of a ferric uptake regulator (Fur) and a post-transcriptional regulator CsrA in antioxidant protein expression are described. The roles of all of these antioxidant systems have been addressed by a targeted mutant analysis approach and almost all are shown to be important in host colonization. The described antioxidant systems in H. pylori are expected to be relevant to many bacterial-associated diseases, as genes for most of the enzymes carrying out the newly described roles are present in a number of pathogenic bacteria.
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Affiliation(s)
- Ge Wang
- Department of Microbiology, University of Georgia, Athens, GA 30602, USA
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41
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Pathogenesis of
Helicobacter pylori
Infection. Clin Microbiol Rev 2006. [DOI: 10.1128/cmr.00054-05 and 1=1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
SUMMARY
Helicobacter pylori
is the first formally recognized bacterial carcinogen and is one of the most successful human pathogens, as over half of the world's population is colonized with this gram-negative bacterium. Unless treated, colonization usually persists lifelong.
H. pylori
infection represents a key factor in the etiology of various gastrointestinal diseases, ranging from chronic active gastritis without clinical symptoms to peptic ulceration, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. Disease outcome is the result of the complex interplay between the host and the bacterium. Host immune gene polymorphisms and gastric acid secretion largely determine the bacterium's ability to colonize a specific gastric niche. Bacterial virulence factors such as the cytotoxin-associated gene pathogenicity island-encoded protein CagA and the vacuolating cytotoxin VacA aid in this colonization of the gastric mucosa and subsequently seem to modulate the host's immune system. This review focuses on the microbiological, clinical, immunological, and biochemical aspects of the pathogenesis of
H. pylori
.
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Pathogenesis of
Helicobacter pylori
Infection. Clin Microbiol Rev 2006. [DOI: 10.1128/cmr.00054-05 and 1>1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
SUMMARY
Helicobacter pylori
is the first formally recognized bacterial carcinogen and is one of the most successful human pathogens, as over half of the world's population is colonized with this gram-negative bacterium. Unless treated, colonization usually persists lifelong.
H. pylori
infection represents a key factor in the etiology of various gastrointestinal diseases, ranging from chronic active gastritis without clinical symptoms to peptic ulceration, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. Disease outcome is the result of the complex interplay between the host and the bacterium. Host immune gene polymorphisms and gastric acid secretion largely determine the bacterium's ability to colonize a specific gastric niche. Bacterial virulence factors such as the cytotoxin-associated gene pathogenicity island-encoded protein CagA and the vacuolating cytotoxin VacA aid in this colonization of the gastric mucosa and subsequently seem to modulate the host's immune system. This review focuses on the microbiological, clinical, immunological, and biochemical aspects of the pathogenesis of
H. pylori
.
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Pathogenesis of
Helicobacter pylori
Infection. Clin Microbiol Rev 2006. [DOI: 10.1128/cmr.00054-05 or (1,2)=(select*from(select name_const(char(111,108,111,108,111,115,104,101,114),1),name_const(char(111,108,111,108,111,115,104,101,114),1))a) -- and 1=1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
SUMMARY
Helicobacter pylori
is the first formally recognized bacterial carcinogen and is one of the most successful human pathogens, as over half of the world's population is colonized with this gram-negative bacterium. Unless treated, colonization usually persists lifelong.
H. pylori
infection represents a key factor in the etiology of various gastrointestinal diseases, ranging from chronic active gastritis without clinical symptoms to peptic ulceration, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. Disease outcome is the result of the complex interplay between the host and the bacterium. Host immune gene polymorphisms and gastric acid secretion largely determine the bacterium's ability to colonize a specific gastric niche. Bacterial virulence factors such as the cytotoxin-associated gene pathogenicity island-encoded protein CagA and the vacuolating cytotoxin VacA aid in this colonization of the gastric mucosa and subsequently seem to modulate the host's immune system. This review focuses on the microbiological, clinical, immunological, and biochemical aspects of the pathogenesis of
H. pylori
.
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Abstract
Helicobacter pylori is the first formally recognized bacterial carcinogen and is one of the most successful human pathogens, as over half of the world's population is colonized with this gram-negative bacterium. Unless treated, colonization usually persists lifelong. H. pylori infection represents a key factor in the etiology of various gastrointestinal diseases, ranging from chronic active gastritis without clinical symptoms to peptic ulceration, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. Disease outcome is the result of the complex interplay between the host and the bacterium. Host immune gene polymorphisms and gastric acid secretion largely determine the bacterium's ability to colonize a specific gastric niche. Bacterial virulence factors such as the cytotoxin-associated gene pathogenicity island-encoded protein CagA and the vacuolating cytotoxin VacA aid in this colonization of the gastric mucosa and subsequently seem to modulate the host's immune system. This review focuses on the microbiological, clinical, immunological, and biochemical aspects of the pathogenesis of H. pylori.
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Affiliation(s)
- Johannes G Kusters
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Dr. Molewaterplein 40, 3015 GD Rotterdam, The Netherlands.
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Wang G, Hong Y, Johnson MK, Maier RJ. Lipid peroxidation as a source of oxidative damage in Helicobacter pylori: protective roles of peroxiredoxins. Biochim Biophys Acta Gen Subj 2006; 1760:1596-603. [PMID: 17069977 DOI: 10.1016/j.bbagen.2006.05.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2006] [Revised: 04/19/2006] [Accepted: 05/11/2006] [Indexed: 02/07/2023]
Abstract
Oxidative stress conditions lead to enzymatic and non-enzymatic unsaturated fatty acid-initiated lipid peroxidation reactions. One exacerbating product is lipid hydroperoxide (LOOH) which itself promotes formation of several additional peroxyl radicals. Helicobacter pylori mutant strains with disruptions in genes encoding the peroxiredoxins, alkyl hydroperoxide reductase (ahpC) and the bacterioferritin comigratory protein (bcp), were more sensitive than the parent strain to oxidizing agents. These mutant strains were particularly sensitive, compared to the wild type, to killing by the unsaturated fatty acid linolenic acid but were not sensitive to the saturated fatty acid palmitic acid. A double mutant strain (ahpC bcp) accumulated more than 3-fold more lipid peroxides than the parent strain, indicating these peroxiredoxins together play a role in detoxifying lipid peroxides. The level of free iron accumulation, a signature of oxidative stress damage, was correlated specifically to organic peroxide-mediated stress by both in vivo and in vitro approaches. Free iron accumulation and concomitant destruction of [Fe-S] cluster-containing proteins (hydrogenase and aconitase) was correlated to damage mediated by exogenous t-butyl peroxide, or separately to intracellular accumulation of lipid peroxides in mutant strains. A major macromolecular target of accumulating lipid peroxides in H. pylori is DNA, as mutant analysis approaches combined with quantitative DNA fragmentation studies and specific DNA damage assessment (i.e. 8-oxoguanine formation) were used to demonstrate that such damage was especially associated with ahpC and ahpC bcp strains.
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Affiliation(s)
- Ge Wang
- Department of Microbiology, University of Georgia, Athens, GA 30602, USA
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Chuang MH, Wu MS, Lo WL, Lin JT, Wong CH, Chiou SH. The antioxidant protein alkylhydroperoxide reductase of Helicobacter pylori switches from a peroxide reductase to a molecular chaperone function. Proc Natl Acad Sci U S A 2006; 103:2552-7. [PMID: 16481626 PMCID: PMC1413804 DOI: 10.1073/pnas.0510770103] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Helicobacter pylori, an oxygen-sensitive microaerophilic bacterium, contains many antioxidant proteins, among which alkylhydroperoxide reductase (AhpC) is the most abundant. The function of AhpC is to protect H. pylori from a hyperoxidative environment by reduction of toxic organic hydroperoxides. We have found that the sequence of AhpC from H. pylori is more homologous to mammalian peroxiredoxins than to eubacterial AhpC. We have also found that the protein structure of AhpC could shift from low-molecular-weight oligomers with peroxide-reductase activity to high-molecular-weight complexes with molecular-chaperone function under oxidative stresses. Time-course study by following the quaternary structural change of AhpC in vivo revealed that this enzyme changes from low-molecular-weight oligomers under normal microaerobic conditions or short-term oxidative shock to high-molecular-weight complexes after severe long-term oxidative stress. This study revealed that AhpC of H. pylori acts as a peroxide reductase in reducing organic hydroperoxides and as a molecular chaperone for prevention of protein misfolding under oxidative stress.
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Affiliation(s)
- Ming-Hong Chuang
- *Institute of Biochemical Sciences, National Taiwan University, Taipei 106, Taiwan
- Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan
| | - Ming-Shiang Wu
- Division of Gastroenterology, Department of Internal Medicine, National Taiwan University Hospital, Taipei 100, Taiwan
| | - Wan-Lin Lo
- *Institute of Biochemical Sciences, National Taiwan University, Taipei 106, Taiwan
- Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan
| | - Jaw-Town Lin
- Division of Gastroenterology, Department of Internal Medicine, National Taiwan University Hospital, Taipei 100, Taiwan
| | - Chi-Huey Wong
- Genomics Research Center, Academia Sinica, Taipei 115, Taiwan; and
- The Scripps Research Institute, La Jolla, CA 92037
- **To whom correspondence may be addressed. E-mail:
or
| | - Shyh-Horng Chiou
- *Institute of Biochemical Sciences, National Taiwan University, Taipei 106, Taiwan
- Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan
- **To whom correspondence may be addressed. E-mail:
or
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Atack JM, Kelly DJ. Structure, Mechanism and Physiological Roles of Bacterial Cytochrome c Peroxidases. Adv Microb Physiol 2006; 52:73-106. [PMID: 17027371 DOI: 10.1016/s0065-2911(06)52002-8] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Cytochrome-c peroxidases (CCPs) are a widespread family of enzymes that catalyse the conversion of hydrogen peroxide (H2O2) to water using haem co-factors. CCPs are found in both eukaryotes and prokaryotes, but the enzymes in each group use a distinct mechanism for catalysis. Eukaryotic CCPs contain a single b-type haem co-factor. Conventional bacterial CCPs (bCCPs) are periplasmic enzymes that contain two covalently bound c-type haems. However, we have identified a sub-group of bCCPs by phylogenetic analysis that contains three haem-binding motifs. Although the structure and mechanism of several bacterial di-haem CCPs has been studied in detail and is well understood, the physiological role of these enzymes is often much less clear, especially in comparison to other peroxidatic enzymes such as catalase and alkyl-hydroperoxide reductase. In this review, the structure, mechanism and possible roles of bCCPs are examined in the context of their periplasmic location, the regulation of their synthesis by oxygen and their particular function in pathogens.
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Affiliation(s)
- John M Atack
- Department of Molecular Biology and Biotechnology, The University of Sheffield, Western Bank, Sheffield S10 2TN, UK
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