Inhibition of the Clostridioides difficile Class D β-Lactamase CDD-1 by Avibactam

Avibactam is a potent diazobicyclooctane inhibitor of class A and C beta-lactamases. The inhibitor also exhibits variable activity against some class D enzymes from Gram-negative bacteria; however, its interaction with recently discovered class D beta-lactamases from Gram-positive bacteria has not been studied. Here, we describe microbiological, kinetic, and mass spectrometry studies of the interaction of avibactam with CDD-1, a class D beta-lactamase from the clinically important pathogen Clostridioides difficile, and show that avibactam is a potent irreversible mechanism-based inhibitor of the enzyme. X-ray crystallographic studies at three time-points demonstrate the rapid formation of a stable CDD-1-avibactam acyl-enzyme complex and highlight differences in the anchoring of the inhibitor by class D enzymes from Gram-positive and Gram-negative bacteria.

Automated summary

Avibactam is a potent irreversible mechanism-based inhibitor of class A and C beta-lactamases, with variable activity against some class D enzymes from Gram-negative bacteria. The interaction of avibactam with recently discovered class D beta-lactamases from Gram-positive bacteria has not been studied. X-ray crystallographic studies demonstrate the rapid formation of a stable CDD-1-avibactam acyl-enzyme complex and differences in anchoring of the inhibitor by class D enzymes from Gram-positive and Gram-negative bacteria.