University of South Florida College of Medicine, Department of Molecular Medicine, 12901 Bruce B. Downs Boulevard, MDC 3522, Tampa, Florida 33612, USA.
J Med Chem. 2012 Mar 8;55(5):2163-72. doi: 10.1021/jm2014138. Epub 2012 Feb 14.
The emergence of CTX-M class A extended-spectrum β-lactamases poses a serious health threat to the public. We have applied structure-based design to improve the potency of a novel noncovalent tetrazole-containing CTX-M inhibitor (K(i) = 21 μM) more than 200-fold via structural modifications targeting two binding hot spots, a hydrophobic shelf formed by Pro167 and a polar site anchored by Asp240. Functional groups contacting each binding hot spot independently in initial designs were later combined to produce analogues with submicromolar potencies, including 6-trifluoromethyl-3H-benzoimidazole-4-carboxylic acid [3-(1H-tetrazol-5-yl)-phenyl]-amide, which had a K(i) value of 89 nM and reduced the MIC of cefotaxime by 64-fold in CTX-M-9 expressing Escherichia coli . The in vitro potency gains were accompanied by improvements in ligand efficiency (from 0.30 to 0.39) and LipE (from 1.37 to 3.86). These new analogues represent the first nM-affinity noncovalent inhibitors of a class A β-lactamase. Their complex crystal structures provide valuable information about ligand binding for future inhibitor design.
CTX-M 类 A 型扩展谱β-内酰胺酶的出现对公众健康构成了严重威胁。我们应用基于结构的设计，通过针对两个结合热点（由 Pro167 形成的疏水性支架和由 Asp240 锚定的极性位点）的结构修饰，将一种新型的非共价含四唑 CTX-M 抑制剂（K(i) = 21 μM）的效力提高了 200 多倍。在最初的设计中，与每个结合热点独立接触的官能团后来被组合在一起，产生了具有亚微摩尔效力的类似物，包括 6-三氟甲基-3H-苯并咪唑-4-羧酸[3-(1H-四唑-5-基)-苯基]-酰胺，其 K(i) 值为 89 nM，并将表达 CTX-M-9 的大肠杆菌中头孢噻肟的 MIC 降低了 64 倍。体外效力的提高伴随着配体效率（从 0.30 提高到 0.39）和 LipE（从 1.37 提高到 3.86）的提高。这些新类似物代表了对 A 类β-内酰胺酶的第一个具有纳摩尔亲和力的非共价抑制剂。它们的复杂晶体结构为未来的抑制剂设计提供了有关配体结合的有价值信息。
