Department of Microbiology and Molecular Biology, Case Western Reserve University, Cleveland, Ohio 44106, USA.
J Med Chem. 2013 Feb 14;56(3):1084-97. doi: 10.1021/jm301490d. Epub 2013 Feb 4.
Inhibitor resistant (IR) class A β-lactamases pose a significant threat to many current antibiotic combinations. The K234R substitution in the SHV β-lactamase, from Klebsiella pneumoniae , results in resistance to ampicillin/clavulanate. After site-saturation mutagenesis of Lys-234 in SHV, microbiological and biochemical characterization of the resulting β-lactamases revealed that only -Arg conferred resistance to ampicillin/clavulanate. X-ray crystallography revealed two conformations of Arg-234 and Ser-130 in SHV K234R. The movement of Ser-130 is the principal cause of the observed clavulanate resistance. A panel of boronic acid inhibitors was designed and tested against SHV-1 and SHV K234R. A chiral ampicillin analogue was discovered to have a 2.4 ± 0.2 nM K(i) for SHV K234R; the chiral ampicillin analogue formed a more complex hydrogen-bonding network in SHV K234R vs SHV-1. Consideration of the spatial position of Ser-130 and Lys-234 and this hydrogen-bonding network will be important in the design of novel antibiotics targeting IR β-lactamases.
A 类β-内酰胺酶抑制剂对许多当前的抗生素组合构成了重大威胁。肺炎克雷伯氏菌的 SHV β-内酰胺酶中的 K234R 取代导致对氨苄西林/克拉维酸的耐药性。在对 SHV 中的赖氨酸 234 进行定点饱和诱变后，对产生的β-内酰胺酶进行微生物学和生物化学特性分析表明，只有 -Arg 赋予对氨苄西林/克拉维酸的耐药性。X 射线晶体学揭示了 SHV K234R 中 Arg-234 和 Ser-130 的两种构象。Ser-130 的运动是观察到克拉维酸耐药性的主要原因。设计并测试了一组硼酸抑制剂对 SHV-1 和 SHV K234R。发现一种手性氨苄西林类似物对 SHV K234R 的 K(i)值为 2.4±0.2 nM；与 SHV-1 相比，手性氨苄西林类似物在 SHV K234R 中形成了更复杂的氢键网络。考虑 Ser-130 和 Lys-234 的空间位置以及该氢键网络在手性氨苄西林类似物对 SHV K234R 的设计中非常重要。
