High tolerance to mutations in a Chlamydia trachomatis peptide deformylase loop

Modifying loop regions in lipase from Caldibacillus thermoamylovorans for enhancing thermostability

Lipases are widely used as green industrial catalysts. Lipases from thermophilic microorganisms are particularly valuable due to their expected thermostability. However, the natural catalytic abilities and tolerance to extreme conditions of most enzymes are often not directly suited to the demands of industrial applications. Enzyme thermostability is closely associated with its structure, making it a target for improving enzyme thermostability. Therefore, we obtained the crystal structure of lipase from Caldibacillus thermoamylovorans (CtLip) with a resolution of 2.2 Å using X-ray diffraction and identified its optimal temperature at 50 °C, with a half-life (t1/2) of 21.59 min at 50 °C. Mutants B1 (R269E/G270S/V271I/V272L), A335I and the stacked mutant B1/A335I (R269E/G270S/V271I/V272L/A335I) in loop region were constructed under the guidance of molecular dynamics analysis. Optimal temperature of mutant B1/A335I increased by 5 °C, with a half-life 8.36 times longer than that of the wild-typed. Our findings provide strategies to improve lipase thermostability by modification of the loop region of the enzyme.

Non-coding nucleotides and amino acids near the active site regulate peptide deformylase expression and inhibitor susceptibility in Chlamydia trachomatis

Chlamydia trachomatis, an obligate intracellular bacterium, is a highly prevalent human pathogen. Hydroxamic-acid-based matrix metalloprotease inhibitors can effectively inhibit the pathogen both in vitro and in vivo, and have exhibited therapeutic potential. Here, we provide genome sequencing data indicating that peptide deformylase (PDF) is the sole target of the inhibitors in this organism. We further report molecular mechanisms that control chlamydial PDF (cPDF) expression and inhibition efficiency. In particular, we identify the σ⁶⁶-dependent promoter that controls cPDF gene expression and demonstrate that point mutations in this promoter lead to resistance by increasing cPDF transcription. Furthermore, we show that substitution of two amino acids near the active site of the enzyme alters enzyme kinetics and protein stability.