Original Article
Copyright ©2011 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Biol Chem. May 26, 2011; 2(5): 90-97
Published online May 26, 2011. doi: 10.4331/wjbc.v2.i5.90
High tolerance to mutations in a Chlamydia trachomatis peptide deformylase loop
Christopher B Oey, Xiaofeng Bao, Christal Lewis, John E Kerrigan, Huizhou Fan
Christopher B Oey, Xiaofeng Bao, Christal Lewis, Huizhou Fan, Department of Physiology and Biophysics, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway, NJ 08854, United States
John E Kerrigan, Cancer Institute of New Jersey, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway, New Brunswick, NJ 08903, United States
Author contributions: Oey CB and Bao X made equal contributions to this work; Fan H and Kerrigan JE designed the study; Oey CB, Bao X, Lewis C and Kerrigan JE performed the experiments; Fan H and Kerrigan JE analyzed the data and wrote the manuscript.
Supported by A grant from the National Institutes of Health (AI071954) to Fan H
Correspondence to: Huizhou Fan, MD, PhD, Department of Physiology and Biophysics, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, 683 Hoes Lane, Piscataway, NJ 08854, United States. fanhu@umdnj.edu
Telephone: +1-732-2354607 Fax: +1-732-2355038
Received: April 9, 2011
Revised: April 27, 2011
Accepted: May 4, 2011
Published online: May 26, 2011
Abstract

AIM: To determine if and how a loop region in the peptide deformylase (PDF) of Chlamydia trachomatis regulates enzyme function.

METHODS: Molecular dynamics simulation was used to study a structural model of the chlamydial PDF (cPDF) and predict the temperature factor per residue for the protein backbone atoms. Site-directed mutagenesis was performed to construct cPDF variants. Catalytic properties of the resulting variants were determined by an enzyme assay using formyl-Met-Ala-Ser as a substrate.

RESULTS: In silico analysis predicted a significant increase in atomic motion in the DGELV sequence (residues 68-72) of a loop region in a cPDF mutant, which is resistant to PDF inhibitors due to two amino acid substitutions near the active site, as compared to wild-type cPDF. The D68R and D68R/E70R cPDF variants demonstrated significantly increased catalytic efficiency. The E70R mutant showed only slightly decreased efficiency. Although deletion of residues 68-72 resulted in a nearly threefold loss in substrate binding, this deficiency was compensated for by increased catalytic efficiency.

CONCLUSION: Movement of the DGELV loop region is involved in a rate-limiting conformational change of the enzyme during catalysis. However, there is no stringent sequence requirement for this region for cPDF enzyme activity.

Keywords: Antibacterial; Chlamydia; Peptide deformylase; Sexually transmitted infection