头孢他啶/阿维巴坦
突变体
化学
立体化学
基质(水族馆)
肺炎克雷伯菌
元动力学
酶
活动站点
生物
生物化学
分子动力学
计算化学
大肠杆菌
生态学
基因
作者
Diksha Parwana,Jing Gu,Shuang Chen,Christopher R. Bethel,Emma Marshall,Andrea M. Hujer,Robert A. Bonomo,Shozeb Haider
标识
DOI:10.1101/2023.05.22.541848
摘要
Abstract The amino acid substitutions in Klebsiella pneumoniae carbapenemase 2 (KPC-2) that have arisen in the clinic are observed to lead to the development of resistance to ceftazidime-avibactam, a preferred treatment for KPC bearing Gram-negative bacteria. Specific substitutions in the omega loop (R164-D179) results in changes in the structure and function of the enzyme, leading to alterations in substrate specificity, decreased stability, and more recently observed, increased resistance to ceftazidime/avibactam. Using accelerated rare-event sampling well-tempered metadynamics simulations, we explored in detail the structural role of R164 and D179 variants that are described to confer ceftazidime/avibactam resistance. The buried conformation of D179 substitutions produce a pronounced structural disorder in the omega loop - more than R164 mutants, where the crystallographic omega loop structure remains mostly intact. Our findings also reveal that the conformation of N170 plays an underappreciated role impacting drug binding and restricting deacylation. The results further support the hypothesis that KPC-2 D179 variants employ substrate-assisted catalysis for ceftazidime hydrolysis, involving the ring amine of the aminothiazole group to promote deacylation and catalytic turnover. Moreover, the shift in the WT conformation of N170 contributes to reduced deacylation and altered spectrum of enzymatic activity.
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