Mapping the binding site of class D beta-lactamase enzymes for inhibitor design a

描述（由申请人提供）：？-内酰胺类药物，如青霉素和头孢菌素，是目前临床使用最广泛的抗生素。由于这些药物的广泛使用和误用，耐药性已经出现，现在已成为21世纪最紧迫的公共卫生危机之一。许多耐药细菌表达？内酰胺酶的酶。这些酶水解内酰胺环，使它们对最初的目标，即与细菌细胞壁交联的转肽酶失去活性。？-内酰胺酶根据序列相似性和作用机制可分为A、B、C、D四类。为了克服耐药性，已经开发出抑制剂来阻断这些酶的活性。特别值得关注的是D类？-内酰胺酶，或者oxacillinases，它们通常不被经典的？-内酰胺类抑制剂，如克拉维酸，能够水解几种最有效的？临床使用的-内酰胺类药物，氧亚胺类头孢菌素和碳青霉烯类药物。在某种程度上，耐药性来自于抑制剂与？-内酰胺本身，都含有？内酰胺环。因此，迫切需要新的抑制剂，不像？内酰胺基板。然而，大多数基于结构的设计工作依赖于对现有结构的修改。内酰胺抗生素。很少有人尝试正式绘制出目标活性位点的结合决定因子，以帮助发现一种新的，非-？内酰胺酶抑制剂。该提案提供了一种综合的方法来正式绘制D ？-内酰胺酶，OXA-1和OXA- 24/40，两个高度相关的抗生素耐药靶点。本提案的具体目的是采用基于结构的共识覆盖方法来识别和表征OXA-1和OXA-40的结合位点。从这个结合位点的共识图中获得的信息将用于发现新的，非？这些关键抗性酶的-内酰胺抑制剂使用分子对接。

DESCRIPTION (provided by applicant): ?-lactams, like penicillin and the cephalosporins, are the most widely prescribed class of antibiotics in clinical use today. In response to their extensive use and misuse, resistance has developed and is now one of the most pressing public health crises of the 21st century. Many resistant bacteria express ?-lactamase enzymes. These enzymes hydrolyze the defining lactam ring, rendering them inactive toward their original target, the transpeptidases that crosslink the bacterial cell wall. ?-lactamases are categorized into four, distinct classes (A, B, C, and D) based on sequence similarity and mechanism of action. In an effort to overcome resistance, inhibitors have been developed to block the activity of these enzymes. Of particular concern are the class D ?-lactamases, or oxacillinases, which are not typically inhibited by the classic ?-lactam- based inhibitors, like clavulanic acid, and are able to hydrolyze several of the most potent ?-lactams in clinical use, the oxyimino cephalosporins and the carbapenems. In part, resistance derives from the structural similarity of the inhibitors to the ?-lactams themselves, both containing a ?-lactam ring. Therefore an urgent need exists for novel inhibitors that do not resemble the ?-lactam substrates. However most structure-based design efforts rely on modification of existing ?-lactam antibiotics. Few attempts have been made to formally map out the binding determinants of a target active site to aid in the discovery of a novel, non-?-lactam inhibitor. This proposal offers a combined approach to formally map the active sites of the class D ?-lactamases, OXA-1 and OXA- 24/40, two highly relevant antibiotic resistance targets. The specific aims of this proposal employ a structure-based consensus overlay approach to identify and characterize the binding sites of OXA-1 and OXA-40. Information from this consensus map of binding sites will be used to discover novel, non-?-lactam inhibitors for these key resistance enzymes using molecular docking. PUBLIC HEALTH RELEVANCE: Currently, antibiotic resistance is one of the most pressing public health crises of the 21st century, and ?-lactamases are the most widespread resistance mechanism to ?-lactam antibiotics. The proposed research is relevant to the mission of the NIH because a better understanding of the structure-function relationship of the class D ?-lactamases OXA-1 and OXA-24/40 will aid in the design and discovery of novel inhibitors for these key targets in bacterial resistance to ?-lactam antibiotics.