Laboratorio de Resistencia Bacteriana, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junin 956, (1113) Buenos Aires, Argentina.
J Antimicrob Chemother. 2012 Oct;67(10):2379-87. doi: 10.1093/jac/dks231. Epub 2012 Jul 6.
Our aim was to unravel the inactivation pathway of the class A β-lactamase produced by Bacillus licheniformis BS3 (BS3) by clavulanate.
The interaction between clavulanate and BS3 was studied by X-ray crystallography, pre-steady-state kinetics and mass spectrometry.
The analysis of the X-ray structure of the complex yielded by the reaction between clavulanate and BS3 indicates that the transient inactivated form, namely the cis-trans enamine complex, is hydrolysed to an ethane-imine ester covalently linked to the active site serine and a pentan-3-one-5-ol acid. It is the first time that this mechanism has been observed in an inactivated β-lactamase. Furthermore, the ionic interactions made by the carboxylic group of pentan-3-one-5-ol may provide an understanding of the decarboxylation process of the trans-enamine observed in the non-productive complex observed for the interaction between clavulanate and SHV-1 and Mycobacterium tuberculosis β-lactamase (Mtu).
This work provides a comprehensive clavulanate hydrolysis pathway accounting for the observed acyl-enzyme structures of class A β-lactamase/clavulanate adducts.
本研究旨在揭示地衣芽孢杆菌 BS3（BS3）产生的 A 类β-内酰胺酶被克拉维酸失活的途径。
通过 X 射线晶体学、预稳态动力学和质谱分析研究克拉维酸与 BS3 的相互作用。
反应生成的克拉维酸与 BS3 复合物的 X 射线结构分析表明，瞬态失活形式，即顺反式烯胺复合物，水解为与活性位点丝氨酸共价结合的乙烷亚胺酯和戊酮-3-醇-5-酸。这是首次在失活的β-内酰胺酶中观察到这种机制。此外，戊酮-3-醇-5-酸的羧酸基团形成的离子相互作用可能有助于理解克拉维酸与 SHV-1 和结核分枝杆菌β-内酰胺酶（Mtu）相互作用中观察到的非生产性复合物中观察到的反式烯胺的脱羧过程。
本研究提供了一个全面的克拉维酸水解途径，解释了 A 类β-内酰胺酶/克拉维酸加合物观察到的酰基-酶结构。
