High tolerance to mutations in a Chlamydia trachomatis peptide deformylase loop

Area of Science:

• Biochemistry
• Structural Biology
• Enzymology

Background:

• Peptide deformylase (PDF) is essential for bacterial protein synthesis.
• Chlamydia trachomatis PDF (cPDF) is a potential drug target.
• Understanding cPDF's structural dynamics is key to inhibitor development.

Purpose of the Study:

• To investigate the role of a specific loop region in cPDF enzyme function.
• To determine how this loop affects catalytic activity and inhibitor resistance.

Main Methods:

• Molecular dynamics simulations to analyze protein flexibility.
• Site-directed mutagenesis to create cPDF variants.
• Enzyme assays to measure catalytic efficiency.

Main Results:

• In silico analysis revealed increased motion in the DGELV loop (residues 68-72) of inhibitor-resistant cPDF mutants.
• cPDF variants with mutations in this loop (D68R, D68R/E70R) showed significantly enhanced catalytic efficiency.
• Deletion of the DGELV loop reduced substrate binding but was compensated by increased catalytic efficiency.

Conclusions:

• The DGELV loop's movement is crucial for a rate-limiting step in cPDF catalysis.
• The enzyme activity does not strictly depend on the DGELV loop's specific sequence.