Thioesterase Inhibitors of Mycolic Acid Biosynthesis as Antitubercular Agents

描述（由申请人提供）：结核分枝杆菌（Mycobacterium tuberculosis）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。这种生长缓慢的生物体的一个主要特征是难以治疗的厚蜡状细胞壁，为许多药物提供了内在屏障。分枝菌酸代表分枝杆菌细胞包膜的中心组分之一，并且是生存所必需的。一线药物异烟肼抑制参与分枝菌酸生物合成早期阶段的InhA酶;然而，对这种药物的耐药性促使人们研究参与分枝菌酸合成的其他潜在酶靶点。最近，一种称为PKS 13的单峰聚酮合酶被鉴定出来，它完成最终的生物合成操作，生成分枝菌酸。聚酮脱氢酶是一种多功能酶，在过去的十年中，由于其参与生物活性天然产物的合成（称为组合生物合成）而受到广泛的研究。PKS参与分枝菌酸合成的发现揭示了这些迷人的酶的一个更险恶的角色。将合成针对Pks 13关键结构域之一的合理设计的小分子抑制剂。将使用无细胞酶测定法测定其体外活性。将采用基于结构和基于配体的计算方法来深入了解观察到的活性数据。将针对全细胞M进一步评价活性化合物。结核将进行脂质分析和微阵列分析的组合，以验证拟定的作用机制。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抗结核化合物，靶向分枝菌酸生物合成的倒数第二步。此外，这种策略可以适用于抑制来自其他病原微生物的关键PKS。

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.