State Key Laboratory of Chemical Biology and Drug Discovery, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.
Department of Infectious Diseases and Public Health, City University of Hong Kong, Kowloon, Hong Kong.
Int J Mol Sci. 2022 Apr 19;23(9):4496. doi: 10.3390/ijms23094496.
The chromosomal -type gene encodes carbapenem-hydrolyzing class D β-lactamases (CHDLs), specific variants shown to mediate carbapenem resistance in the Gram-negative bacterial pathogen . This study aims to characterize the effect of key amino acid substitutions in OXA-51 variants of carbapenem-hydrolyzing class D β-lactamases (CHDLs) on substrate catalysis. Mutational and structural analyses indicated that each of the L167V, W222G, or I129L substitutions contributed to an increase in catalytic activity. The I129L mutation exhibited the most substantial effect. The combination of W222G and I129L substitutions exhibited an extremely strong catalytic enhancement effect in OXA-66, resulting in higher activity than OXA-23 and OXA-24/40 against carbapenems. These findings suggested that specific arrangement of residues in these three important positions in the intrinsic OXA-51 type of enzyme can generate variants that are even more active than known CHDLs. Likewise, mutation leading to the W222M change also causes a significant increase in the catalytic activity of OXA-51. gene in A. baumannii may likely continue to evolve, generating mutant genes that encode carbapenemase with extremely strong catalytic activity.
该染色体型基因编码碳青霉烯水解的 D 类β-内酰胺酶（CHDLs），特定变体被证明可介导革兰氏阴性细菌病原体中的碳青霉烯耐药性。本研究旨在表征碳青霉烯水解的 D 类β-内酰胺酶（CHDLs）中 OXA-51 变体的关键氨基酸取代对底物催化的影响。突变和结构分析表明，L167V、W222G 或 I129L 取代中的每一种都有助于增加催化活性。I129L 突变表现出最显著的效果。W222G 和 I129L 取代的组合在 OXA-66 中表现出极强的催化增强效应，导致对碳青霉烯的活性高于 OXA-23 和 OXA-24/40。这些发现表明，在固有 OXA-51 型酶的这三个重要位置中特定的残基排列可以产生比已知 CHDLs 更具活性的变体。同样，导致 W222M 变化的突变也会导致 OXA-51 的催化活性显著增加。鲍曼不动杆菌中 blaOXA-51 基因可能会继续进化，产生编码具有极强催化活性的碳青霉烯酶的突变基因。
