Thioesterase Inhibitors of Mycolic Acid Biosynthesis as Antitubercular Agents

描述(申请人提供)：结核分枝杆菌是结核病(TB)的病原体，是世界上由细菌病原体引起的传染病死亡的主要原因。这种生长缓慢的有机体的一个主要特征是厚厚的蜡状细胞壁，它为许多药物提供了内在的屏障，这使得治疗变得困难。霉菌酸是分枝杆菌细胞膜的中心成分之一，是生存所必需的。一线药物异烟肼抑制了参与霉菌酸生物合成早期阶段的inha酶；然而，对该药物的抗药性促使人们研究与霉菌酸合成有关的其他潜在酶靶标。最近，一种被称为PKS 13的单峰聚酮合成酶被鉴定出来，它执行最终的生物合成操作，导致霉菌酸。聚酮合成酶是一种多功能的酶，在过去的十年里，由于它们参与了生物活性天然产物的合成，被称为组合生物合成，因此受到了广泛的研究。PKS参与了真菌酸的合成，这一发现揭示了这些令人着迷的酶的一个更险恶的作用。针对Pks 13关键结构域之一的合理设计的小分子抑制剂将被合成。将使用无细胞酶试验来检测这些物质的体外活性。基于结构和基于配体的计算方法将被用来提供对观察到的活动数据的洞察。活性化合物将进一步评估对全细胞结核分枝杆菌的作用。将结合脂质分析和微阵列分析来验证所提出的作用机制。这项拟议的研究有望验证Pks 13作为药物靶点，并可能导致一类新的针对霉菌酸生物合成倒数第二步的抗结核化合物。此外，这一策略可能适用于抑制来自其他病原微生物的关键PKSS。

DESCRIPTION (provided by applicant): Mycobacterium tuberculosis the causative agent of Tuberculosis (TB) is the leading cause of infectious disease mortality in the world by a bacterial pathogen. A primary feature of this slow-growing organism that makes it difficult to treat is the thick waxy cell wall that provides an intrinsic barrier to many drugs. The mycolic acids represent one of the central components of the mycobacterial cell envelope and are essential for survival. The first-line drug isoniazid inhibits the enzyme known as InhA involved in early stages of mycolic acid biosynthesis; however, resistance to this agent has prompted research into other potential enzyme targets involved in mycolic acid synthesis. Recently, a monomodular polyketide synthase known as pks 13 was identified that performs the final biosynthetic operation leading to mycolic acids. Polyketide synthases are multifunctional enzymes and have been intensively investigated in the last decade for their involvement in the synthesis of bioactive natural products, a field termed combinatorial biosynthesis. The findings that PKSs are involved in the synthesis of the mycolic acids uncover a more sinister role for these fascinating enzymes. Rationally designed small-molecule inhibitors targeting one of the crucial domains of Pks13 will be synthesized. These will be assayed for in vitro activity using a cell-free enzyme assay. Structure-based and ligand-based computational methods will be employed to provide insight into the observed activity data. Active compounds will be further evaluated against whole-cell M. tuberculosis. A combination of lipid analysis and microarray profiling will be performed to verify the proposed mechanism of action. This proposed research is expected to validate Pks13 as a drug target and may lead to a new class of antitubercular compounds that target the penultimate step of mycolic acid biosynthesis. Additionally, this strategy may be adapted to inhibit critical PKSs from other pathogenic microorganisms.