Inhibitors of Staphylococcus aureus NaMN adenylyltransferase NadD

描述（由申请人提供）：常见细菌病原体的多药耐药菌株的快速传播对公共卫生构成了重大威胁，需要加快努力开发针对以前未探索的靶点的新型抗生素。最值得注意的是，许多金黄色葡萄球菌菌株（医院感染的主要来源）对常用抗生素具有耐药性。比较基因组学分析和基因必要性研究表明，NadD家族的烟酸单核苷酸（NaMN）腺苷酰转移酶是大多数细菌（包括S.金黄色葡萄球菌）作为开发新型抗微生物剂的突出靶标。在先前的研究中，首先，鉴定了来自代表性革兰氏阳性和革兰氏阴性细菌的NadD酶的小分子抑制剂，然后证实了它们的靶向抗菌活性。部分化合物对沙门氏菌也有较强的抑制活性。金黄色葡萄球菌NadD酶。这些结果提供了NadD目标的验证，并为寻找具有显著改善的亲和力，选择性和抗菌特性的新抑制剂奠定了基础。 本研究拟通过以下具体目标实现这一目标：（1）筛选MLPCN小分子化合物文库，并进行命中优化以鉴定高亲和力的S.金黄色葡萄球菌NadD酶（IC 50 d1 μ M）;（II）通过二级测定和计数器筛选对功能性但结构不同的人酶进行测试确认命中;（III）评估选定指定探针的抗菌特性和动力学机制。所提出的项目的可行性得到了纯重组靶酶的可用性以及在初步研究中开发的HTS测定方法的支持。选择最好的抑制剂将在未来的工作中作为分子探针，以进一步探索NAD生物合成作为开发新抗生素的靶向途径。

DESCRIPTION (provided by applicant): The rapid spread of multidrug-resistant strains of common bacteria pathogens pose a significant threat to public health, calling for an accelerated effort to develop novel antibiotics acting on previously unexplored targets. Most notably, many strains of Staphylococcus aureus, a major source of infections in hospitals, are resistant to commonly used antibiotics. Comparative genomics analysis and gene essentiality studies implicated nicotinic acid mononucleotide (NaMN) adenylyltransferase of the NadD family, the key indispensable enzyme in NAD biogenesis of most bacteria (including S. aureus), as a prominent target for the development of novel antimicrobial agents. In previous studies, first, small molecule inhibitors of NadD enzymes from representative gram-positive and gram-negative bacteria were identified, and then their on- target antibacterial activity was confirmed. Some of the identified compounds also showed strong inhibitory activity against S. aureus NadD enzyme. These results provided validation of the NadD target and set the stage for searching for new inhibitors with substantially improved affinity, selectivity, and antibacterial properties. This goal would be addressed in the proposed project by pursuing the following specific aims: (I) screen the MLPCN small molecule compound library and perform hit optimization to identify high-affinity inhibitors of S. aureus NadD enzyme (with IC50 d1 microM); (II) test confirmed hits by secondary assays and in the counter screen against is functional but structurally distinct human enzyme; (III) assess antibacterial properties and kinetic mechanisms of selected nominated probes. The feasibility of the proposed project is supported by the availability of the pure recombinant target enzyme as well as HTS assay methods developed in preliminary studies. Selected best inhibitors will be used in future work as molecular probes to further explore NAD biosynthesis as a target pathway for the development of novel antibiotics.