Energetic, structural, and antimicrobial analyses of β-lactam side chain recognition by β-lactamases
Energetic, structural, and antimicrobial analyses of β-lactam side chain recognition by β-lactamases
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DOI：
10.1016/s1074-5521(00)00052-1
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发表时间：
2001-01-01
影响因子：
--
通讯作者：
Shoichet, BK
中科院分区：
文献类型：
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作者：
Caselli, E;Powers, RA;Shoichet, BK
背景：青霉素类和头孢菌素类是应用最广泛、最成功的抗生素之一。对这些β-内酰胺类抗生素的耐药性的出现，通常是通过细菌对β-内酰胺酶的表达，威胁着公众健康。要了解β-内酰胺酶如何识别它们的底物，知道它们的结合能将是有帮助的。不幸的是，这些都很难测量，因为β-内酰胺类药物与β-内酰胺酶形成共价加合物。结果：为了研究β-内酰胺类抗生素的关键酰胺(R1)侧链对相互作用能的贡献，合成了8个带有特征青霉素和头孢菌素侧链的酰基甘草酸和4个类似物。这些过渡态类似物与丝氨酸β-内酰胺酶形成可逆加合物。因此，可以直接从K-I值计算结合能，针对I组β-内酰胺酶AmpC测得的K-I值跨越四个数量级，针对II组β-内酰胺酶TEM-1测得的K-I值跨越三个数量级。酰基甘草酸对AmpC的K-I值低至20 nM，对TEM1I的K-I值低至390 nM。这些抑制剂对丝氨酸蛋白酶表现出很小的活性，例如凝乳酶。β-内酰胺抑制剂特有的R1侧链与AmpC的亲和力并不比β-内酰胺底物特有的侧链更强。其中两种抑制剂在细胞培养中逆转了病原菌对β-内酰胺类药物的耐药性。两种抑制剂与AmpC形成的络合物的结构由1.90埃和1.75埃分辨率的X射线结晶学确定；这些结构表明相互作用对抑制剂的亲和力是重要的。结论：酰基甘氨酸硼酸使我们可以开始剖析β-内酰胺侧链和β-内酰胺酶之间的相互作用能，令人惊讶的是，R1侧链的亲和力与它们在β-内酰胺酶抑制剂或β-内酰胺酶底物中的出现几乎没有相关性。然而，这些侧链存在于酰基甘油基硼酸中，可以导致高亲和力和特异性的缓蚀剂，它们与AMPC的络合物的结构为它们的亲和力提供了分子背景，并可能指导该系列抗耐药化合物的设计。(C)2001爱思唯尔科学有限公司，保留所有权利。
Background: Penicillins and cephalosporins are among the most widely used and successful antibiotics. The emergence of resistance to these beta -lactams, most often through bacterial expression of beta -lactamases, threatens public health. To understand how beta -lactamases recognize their substrates, it would be helpful to know their binding energies. Unfortunately, these have been difficult to measure because beta -lactams form covalent adducts with beta -lactamases. This has complicated functional analyses and inhibitor design.Results: To investigate the contribution to interaction energy of the key amide (R1) side chain of beta -lactam antibiotics, eight acylglycineboronic acids that bear the side chains of characteristic penicillins and cephalosporins, as well as four other analogs, were synthesized. These transition-state analogs form reversible adducts with serine beta -lactamases. Therefore, binding energies can be calculated directly from K-i values, The K-i values measured span four orders of magnitude against the Group I beta -lactamase AmpC and three orders of magnitude against the Group II beta -lactamase TEM-1. The acylglycineboronic acids have K-i values as low as 20 nM against AmpC and as low as 390 nM against TEM1I. The inhibitors showed little activity against serine proteases, such as chymotrypsin. R1 side chains characteristic of beta -lactam inhibitors did not have better affinity for AmpC than did side chains characteristic of beta -lactam substrates. Two of the inhibitors reversed the resistance of pathogenic bacteria to beta -lactams in cell culture. Structures of two inhibitors in their complexes with AmpC were determined by X-ray Crystallography to 1.90 Angstrom and 1.75 Angstrom resolution; these structures suggest interactions that are important to the affinity of the inhibitors.Conclusions: Acylglycineboronic acids allow us to begin to dissect interaction energies between beta -lactam side chains and beta -lactamases, Surprisingly, there is little correlation between the affinity contributed by R1 side chains and their occurrence in beta -lactum inhibitors or beta -lactam substrates of serine p-lactamases. Nevertheless, presented in acylglycineboronic acids, these side chains can lead to inhibitors with high affinities and specificities, The structures of their complexes with AmpC give a molecular context to their affinities and may guide the design of antiresistance compounds in this series. (C) 2001 Elsevier Science Ltd, All rights reserved.