5G18

Direct Observation of Active-site Protonation States in a Class A beta lactamase with a monobactam substrate

5G18 の概要

• エントリーDOI: 10.2210/pdb5g18/pdb
• 分子名称: BETA-LACTAMASE CTX-M-97, 2-({[(1Z)-1-(2-amino-1,3-thiazol-4-yl)-2-oxo-2-{[(2S,3S)-1-oxo-3-(sulfoamino)butan-2-yl]amino}ethylidene]amino}oxy)-2-methylpropanoic acid, SULFATE ION, ... (4 entities in total)
• 機能のキーワード: hydrolase, beta lactamase, toho, neutron
• 由来する生物種: ESCHERICHIA COLI
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 29035.52

構造登録者

Vandavasi, V.G.,Weiss, K.L.,Parks, J.M.,Cooper, J.B.,Ginell, S.L.,Coates, L. (登録日: 2016-03-23, 公開日: 2016-11-09, 最終更新日: 2024-10-16)

主引用文献

Vandavasi, V.G.,Langan, P.S.,Weiss, K.L.,Parks, J.M.,Cooper, J.B.,Ginell, S.L.,Coates, L.
Active-Site Protonation States in an Acyl-Enzyme Intermediate of a Class A beta-Lactamase with a Monobactam Substrate.
Antimicrob. Agents Chemother., 61:-, 2017

PubMed Abstract: The monobactam antibiotic aztreonam is used to treat cystic fibrosis patients with chronic pulmonary infections colonized by Pseudomonas aeruginosa strains expressing CTX-M extended-spectrum β-lactamases. The protonation states of active-site residues that are responsible for hydrolysis have been determined previously for the apo form of a CTX-M β-lactamase but not for a monobactam acyl-enzyme intermediate. Here we used neutron and high-resolution X-ray crystallography to probe the mechanism by which CTX-M extended-spectrum β-lactamases hydrolyze monobactam antibiotics. In these first reported structures of a class A β-lactamase in an acyl-enzyme complex with aztreonam, we directly observed most of the hydrogen atoms (as deuterium) within the active site. Although Lys 234 is fully protonated in the acyl intermediate, we found that Lys 73 is neutral. These findings are consistent with Lys 73 being able to serve as a general base during the acylation part of the catalytic mechanism, as previously proposed.

PubMed: 27795378
DOI: 10.1128/AAC.01636-16

実験手法

X-RAY DIFFRACTION (1.1 Å)