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Publication Abstract from PubMed

The Asp233-Asp246 pair is highly conserved in Class A beta-lactamases, which hydrolyze beta-lactam antibiotics. Here, we characterize its function using CTX-M-14 beta-lactamase. The D233N mutant displayed decreased activity that is substrate-dependent, with reductions in kcat /Km ranging from 20% for nitrocefin to 6-fold for cefotaxime. In comparison, the mutation reduced the binding of a known reversible inhibitor by 10-fold. The mutant structures showed movement of the 213-219 loop and the loss of the Thr216-Thr235 hydrogen bond, which was restored by inhibitor binding. Mutagenesis of Thr216 further highlighted its contribution to CTX-M activity. These results demonstrate the importance of the aspartate pair to CTX-M hydrolysis of substrates with bulky side chains, while suggesting increased protein flexibility as a means to evolve drug resistance.

Mutation of the conserved Asp-Asp pair impairs the structure, function, and inhibition of CTX-M Class A beta-lactamase.,Kemp MT, Nichols DA, Zhang X, Defrees K, Na I, Renslo AR, Chen Y FEBS Lett. 2021 Oct 26. doi: 10.1002/1873-3468.14215. PMID:34704263^[1]

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