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Publication Abstract from PubMed

The predominant resistance mechanism observed in Gram-negative bacteria involves the production of beta-lactamases, which catalyse the hydrolysis of beta-lactam antibiotics, thereby rendering them ineffective. Although Isoxazolyl Penicillins have been available since the 1970s, there are currently no structures in complex with class-A beta-lactamases available. Here we have analysed the structure of the clinically relevant beta-lactamase CTX-M-14 from Klebsiella pneumoniae near physiological temperatures, via serial synchrotron crystallography. We demonstrate the acyl-enzyme intermediates of the catalytically impaired CTX-M-14 mutant E166A in complex with three Isoxazolyl-Penicillins: Oxacillin, Cloxacillin and Dicloxacillin. Structural comparisons of CTX-M-Penicillin complexes show that, while conserved active-site interactions are maintained, each Isoxazolyl-Penicillin adopts a distinct conformation. While the three derivatives differ only by one and two chlorine atoms, respectively, their conformational heterogeneity appears to be increased by chlorination of the phenyl ring.

Binding mode of Isoxazolyl Penicillins to a Class-A beta-lactamase at ambient conditions.,Gore G, Prester A, von Stetten D, Bartels K, Schulz EC Commun Chem. 2025 Dec 1;8(1):387. doi: 10.1038/s42004-025-01801-x. PMID:41326695^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.