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Publication Abstract from PubMed

The extensive use of beta-lactam antibiotics has led to significant resistance, primarily due to hydrolysis by beta-lactamases. OXA class D beta-lactamases can hydrolyze a wide range of beta-lactam antibiotics, rendering many treatments ineffective. We investigated the effects of single amino acid substitutions in OXA-10 on its substrate spectrum. Broad-spectrum variants with point mutations were searched and biochemically verified. Three key residues, G157D, A124T, and N73S, were confirmed in the variants, and their crystal structures were determined. Based on an enzyme kinetics study, the hydrolytic activity against broad-spectrum cephalosporins, particularly ceftazidime, was significantly enhanced by the G157D mutation in loop 2. The A124T or N73S mutation close to loop 2 also resulted in higher ceftazidime activity. All structures of variants with point mutations in loop 2 or nearby exhibited increased loop 2 flexibility, which facilitated the binding of ceftazidime. These results highlight the effect of a single amino acid substitution in OXA-10 on broad-spectrum drug resistance. Structure-activity relationship studies will help us understand the drug resistance spectrum of beta-lactamases, enhance the effectiveness of existing beta-lactam antibiotics, and develop new drugs.

Structural insights into alterations in the substrate spectrum of serine-beta-lactamase OXA-10 from Pseudomonas aeruginosa by single amino acid substitutions.,Lee CE, Park Y, Park H, Kwak K, Lee H, Yun J, Lee D, Lee JH, Lee SH, Kang LW Emerg Microbes Infect. 2024 Dec;13(1):2412631. doi: , 10.1080/22221751.2024.2412631. Epub 2024 Oct 22. PMID:39361442^[1]

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