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

描述(申请人提供)：？-内酰胺类，与青霉素和头孢菌素类一样，是当今临床上使用最广泛的处方类抗生素。由于它们的广泛使用和误用，抗药性已经形成，现在已成为21世纪最紧迫的公共卫生危机之一。许多耐药细菌都表达β-内酰胺酶。这些酶水解定义的内酰胺环，使它们对最初的目标不活跃，转肽酶使细菌细胞壁交联。根据序列相似性和作用机制，内酰胺酶可分为四类(A、B、C和D)。为了克服耐药性，已经开发出了阻断这些酶活性的抑制剂。尤其值得关注的是D？-内酰胺酶或苯唑西林酶，这种酶通常不会被经典的基于β-内酰胺的抑制剂，如克拉维酸所抑制，并且能够降解临床上使用的几种最有效的β-内酰胺类抗生素，即氧化亚氨基头孢菌素和碳青霉烯类。在一定程度上，耐药性源于抑制剂与β-内酰胺类药物本身的结构相似，两者都含有β-内酰胺环。因此，迫切需要一种不同于β-内酰胺底物的新型抑制剂。然而，大多数基于结构的设计工作依赖于对现有的β-内酰胺类抗生素的改造。很少有人尝试正式绘制出靶标活性部位的结合决定因素，以帮助发现一种新型的非内酰胺类抑制剂。这项建议提供了一种组合的方法来正式定位D类内酰胺酶的活性部位，OXA-1和OXA-24/40是两个高度相关的抗生素耐药靶标。该提案的具体目的是采用基于结构的共识重叠方法来识别和表征OXA-1和OXA-40的结合位点。来自结合位点的共识图谱的信息将被用于通过分子对接为这些关键耐药酶发现新型的非内酰胺类抑制剂。 公共卫生相关性：目前，抗生素耐药性是21世纪最紧迫的公共卫生危机之一，而β-内酰胺酶是对β-内酰胺类抗生素最普遍的耐药机制。这项拟议的研究与美国国立卫生研究院的使命有关，因为更好地了解D？-内酰胺酶OXA-1和OXA-24/40的结构与功能关系将有助于设计和发现针对这些细菌对β-内酰胺类抗生素耐药性的关键靶点的新型抑制剂。

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.