Design of multi-target D-Ala-D-Ala ligase ligands

描述（由申请人提供）：结核分枝杆菌是当今的主要流行病，每年在全世界造成800万新发病例和300万死亡。迫切需要通过新机制起作用的新型抗结核药物，以便与现有药物联合进行更有效的治疗，并治疗近年来出现的多药耐药菌株。细菌细胞壁含有肽聚糖，可抵抗外部渗透压。肽聚糖生物合成的靶向步骤是新抗菌剂的一个有吸引力的机制。一个重要步骤是合成D-丙氨酰-D-丙氨酸二肽（D-Ala-D-Ala），这是形成肽聚糖和交联肽聚糖链所必需的。催化该过程的酶是D-丙氨酰-D-丙氨酸连接酶（DDl）。DDl是新抗生素的极好靶点，因为D-Ala-D-Ala的合成是细菌生长的必要过程，而且没有DDl的人等效物。我们已经应用了基于计算机结构的方法来鉴定和测定DDl ATP和底物位点结合配体，使用了已经显示出针对M的活性的化合物组。在HTS筛选和激酶结合配体中，发现结核TB H37 Rv与DDl显示结构相似性。我们建议在所提出的努力的前半部分中改进和验证DDl结合预测方案，并利用这些方案来鉴定和测定基于针对DDl的活性的有效抗结核靶标的已知支架的化合物。 公共卫生相关性：为了更有效地治疗结核病和治疗最近出现的多药耐药菌株，迫切需要通过新机制起作用的新抗结核药物。在该提案中，我们应用了基于计算机模拟结构的方法来鉴定和测定新的有效DDl结合剂和多TB靶配体。

DESCRIPTION (provided by applicant): Mycobacterium tuberculosis is a major epidemic today, causing 8 million new cases and 3 million deaths yearly world-wide. New anti-tubercular drugs that act through novel mechanisms are urgently needed for more efficacious treatments in combination with existing drugs and for treating multi-drug resistant strains that emerged in recent years. The bacterial cell wall contains peptidoglycan that provides resistance from external osmotic pressure. Targeting steps of peptidoglycan biosynthesis is an attractive mechanism for new antibacterial agents. An essential step is the synthesis of D-Alanyl-D-Alanine dipeptide (D-Ala-D-Ala) that is required for the formation of peptidoglycan and for cross-linking peptidoglycan strands. The enzyme catalyzing this process is D-Alanyl-D-Alanine ligase (DDl). DDl is an excellent target for new antibiotics since synthesis of D-Ala-D-Ala is an essential process for bacterial growth and furthermore there is no human equivalent to DDl. We have applied an in silico structure based approach to identify and assay DDl ATP and substrate site binding ligands using sets of compounds that have shown activity against M. tuberculosis TB H37Rv in HTS screening and kinase binding ligands that show structural similarities to DDl. We propose to refine and validate DDl binding prediction protocols in the first half of the proposed effort and utilize these to identify and assay compounds based on known scaffolds of valid anti-tubercular targets for activity against DDl. PUBLIC HEALTH RELEVANCE: New anti-tubercular drugs that act through novel mechanisms are urgently needed for more efficacious treatments of tuberculosis and for treating multi-drug resistant strains that recently emerged. In this proposal we have apply an in silico structure based approach to identify and assay novel potent DDl binders and multi- TB target ligands.