5u53

CTX-M-14 E166A with acylated ceftazidime molecule

spinqualitylabelsall models 5u53, resolution 1.40Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 5u53 is a 1 chain structure with sequence from Escherichia coli. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.4Å Ligands: CAZ, NO3 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function H6UQI0_ECOLX Publication Abstract from PubMed CTX-M beta-lactamases provide resistance against the beta-lactam antibiotic, cefotaxime, but not a related antibiotic, ceftazidime. beta-Lactamases that carry the P167S substitution, however, provide ceftazidime resistance. In this study, CTX-M-14 was used as a model to study the structural changes caused by the P167S mutation that accelerate ceftazidime turnover. X-ray crystallography was used to determine the structures of the P167S apoenzyme along with the structures of the S70G/P167S, E166A/P167S, and E166A mutant enzymes complexed with ceftazidime as well as the E166A/P167S apoenzyme. The S70G and E166A mutations allow capture of the enzyme-substrate complex and the acylated form of ceftazidime, respectively. The results showed a large conformational change in the Omega-loop of the ceftazidime acyl-enzyme complex of the P167S mutant but not in the enzyme-substrate complex, suggesting the change occurs upon acylation. The change results in a larger active site that prevents steric clash between the aminothiazole ring of ceftazidime and the Asn170 residue in the Omega-loop, allowing accommodation of ceftazidime for hydrolysis. In addition, the conformational change was not observed in the E166A/P167S apoenzyme, suggesting the presence of acylated ceftazidime influences the conformational change. Finally, the E166A acyl-enzyme structure with ceftazidime did not exhibit the altered conformation, indicating the P167S substitution is required for the change. Taken together, the results reveal that the P167S substitution and the presence of acylated ceftazidime both drive the structure toward a conformational change in the Omega-loop and that in CTX-M P167S enzymes found in drug-resistant bacteria this will lead to an increased level of ceftazidime hydrolysis. The Drug-Resistant Variant P167S Expands the Substrate Profile of CTX-M beta-Lactamases for Oxyimino-Cephalosporin Antibiotics by Enlarging the Active Site upon Acylation.,Patel MP, Hu L, Stojanoski V, Sankaran B, Prasad BVV, Palzkill T Biochemistry. 2017 Jul 11;56(27):3443-3453. doi: 10.1021/acs.biochem.7b00176., Epub 2017 Jun 27. PMID:28613873 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Beta-lactamase 3D structures

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