Structure of Enterococcus faeciuml,d-transpeptidase acylated by ertapenem provides insight into the inactivation...

Area of Science:

• Microbiology
• Structural Biology
• Drug Discovery

Background:

• Bacterial cell wall integrity relies on peptidoglycan cross-linking, primarily via d,d-transpeptidation catalyzed by penicillin-binding proteins (PBPs).
• l,d-transpeptidases (Ldts) are emerging targets, functionally replacing PBPs in some resistant bacteria like Enterococcus faecium and Mycobacterium tuberculosis.
• Carbapenems are effective suicide substrates inhibiting Ldts, making them vital in combating antibiotic resistance.

Purpose of the Study:

• To elucidate the structural mechanism of carbapenem inhibition of l,d-transpeptidases.
• To provide atomic-level insights into the interaction between ertapenem and Enterococcus faecium Ldtfm.
• To inform the development of novel carbapenem-based antibacterial agents.

Main Methods:

• X-ray crystallography to determine the structure of carbapenem-acylated l,d-transpeptidase.
• Biochemical analysis of enzyme-antibiotic interactions.
• Computational analysis of proton transfer mechanisms.

Main Results:

• The first structure of ertapenem-acylated Enterococcus faecium Ldtfm is presented, detailing key interactions within the catalytic cavity.
• Significant conformational changes in the carbapenem antibiotic upon acylation by the enzyme were observed.
• Analysis revealed crucial protein-to-carbapenem proton transfers involved in the inhibition mechanism.

Conclusions:

• The study provides critical structural insights into the mechanism of l,d-transpeptidase inhibition by carbapenems.
• These findings are essential for understanding antibiotic resistance and designing next-generation carbapenem antibiotics.
• The revealed interactions highlight potential targets for novel antibacterial drug development.