7k2y

Crystal structure of CTX-M-14 E166A/K234R Beta-lactamase in complex with hydrolyzed ampicillin

spinqualitylabelsall models 7k2y, resolution 1.62Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 7k2y is a 1 chain structure with sequence from "bacillus_coli"_migula_1895 "bacillus coli" migula 1895. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: AIX Gene: blaCTX-M ("Bacillus coli" Migula 1895) Activity: Beta-lactamase, with EC number 3.5.2.6 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed Lys(234) is one of the residues present in class A beta-lactamases that is under selective pressure due to antibiotic use. Located adjacent to proton shuttle residue Ser(130), it is suggested to play a role in proton transfer during catalysis of the antibiotics. The mechanism underpinning how substitutions in this position modulate inhibitor efficiency and substrate specificity leading to drug resistance is unclear. The K234R substitution identified in several inhibitor-resistant beta-lactamase variants is associated with decreased potency of the inhibitor clavulanic acid, which is used in combination with amoxicillin to overcome beta-lactamase-mediated antibiotic resistance. Here we show that for CTX-M-14 beta-lactamase, whereas Lys(234) is required for hydrolysis of cephalosporins such as cefotaxime, either lysine or arginine is sufficient for hydrolysis of ampicillin. Further, by determining the acylation and deacylation rates for cefotaxime hydrolysis, we show that both rates are fast, and neither is rate-limiting. The K234R substitution causes a 1500-fold decrease in the cefotaxime acylation rate but a 5-fold increase in k cat for ampicillin, suggesting that the K234R enzyme is a good penicillinase but a poor cephalosporinase due to slow acylation. Structural results suggest that the slow acylation by the K234R enzyme is due to a conformational change in Ser(130), and this change also leads to decreased inhibition potency of clavulanic acid. Because other inhibitor resistance mutations also act through changes at Ser(130) and such changes drastically reduce cephalosporin but not penicillin hydrolysis, we suggest that clavulanic acid paired with an oxyimino-cephalosporin rather than penicillin would impede the evolution of resistance. A drug-resistant beta-lactamase variant changes the conformation of its active-site proton shuttle to alter substrate specificity and inhibitor potency.,Soeung V, Lu S, Hu L, Judge A, Sankaran B, Prasad BVV, Palzkill T J Biol Chem. 2020 Dec 25;295(52):18239-18255. doi: 10.1074/jbc.RA120.016103. Epub, 2020 Oct 26. PMID:33109613 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Beta-lactamase 3D structures

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