Fragment to small molecule hit discovery targeting Mycobacterium tuberculosis FtsZ

结核病（TB）是发展中国家和发达国家发病率和死亡率的主要原因。10.6 2021年，有100万人患上结核病，160万人死于结核病。约有45万例报告病例被归类为耐多药结核病（MDR-TB），其中一部分患者发展为广泛耐药结核病（XDR-TB）。约四分之一的世界人口患有潜伏性结核病，约10-15%的人继续发展和传播感染。患者获得当前治疗以及长期给药方案的依从性是一个全球性挑战。耐多药结核病更难治疗，而新出现的广泛耐药结核病的选择更加有限。开发新型抗结核药物以成功对抗新出现的耐药性是一项迫切的未满足的医疗需求。最近的进展是通过对已知抗结核药物的再利用和再给药来实现的，但在临床试验中没有通过新的作用机制起作用的新药类别。蛋白质“丝状温度敏感突变体Z”（FtsZ）在所有类型的细菌中高度保守，包括导致结核病的分枝杆菌物种。它是一种必需的细胞分裂蛋白，具有GTdR和聚合活性。FtsZ亚基聚合成原丝，形成一个动态的环状结构，称为Z环，其功能是作为分裂体组装的支架，分裂体是一种多蛋白复合物，引起Z环收缩，最终导致隔膜形成和细胞分裂。FtsZ的缺失阻断Z环功能，导致细长的丝状表型，抑制细胞分裂和随后的细胞死亡。虽然FtsZ抑制剂已被鉴定，但大多数来自天然产物，并且通常缺乏结构信息，许多抑制剂被归类为“假阳性”。结核病（MTb）FtsZ的大量生物化学，生物物理和结构研究。与莫纳什NMR筛选设施合作，我们鉴定了38个针对FtsZ的片段命中。我们建立了生物物理（DSF，MST）和生物化学（GTdR，直角散射）测定，以验证其GTdR活性和聚合/解聚动力学。独特的是，我们已经确定了FtsZ的晶体结构与碎片命中复合物，并建立其作用机制。我们已经评估了片段结合位点的片段生长和合并，我们准备启动SAR的目录和定制优化的命中，以开发更有效的类似物。在这个项目中，我们的目标是开发和MTb FtsZ作为一种新的抗生素类治疗结核病感染的强效抑制剂。我们预计，这些化合物将成为结核病及其耐药变体治疗选择的一个受欢迎的补充。这个合作药物发现项目解决了一个明确的未满足的医疗需求。该项目的成功完成将为包括其他UCL合作伙伴在内的更广泛的合作药物发现计划奠定基础。

Tuberculosis (TB) is a major cause of morbidity and mortality in developing and developed countries. 10.6 million people developed the disease and 1.6 million people died from TB in 2021. Approximately 450,000 reported cases are classified as multidrug-resistant tuberculosis (MDR-TB), with a subset of patients developing extensively-drug-resistant tuberculosis (XDR-TB).About a quarter of the world's population have latent TB, with ~10-15% going on to develop and spread the infection. Patient access to current treatments, and compliance with the lengthy dosing regimens is a global challenge. MDR-TB is more difficult to treat, and options for the emerging XDR-TB are even more limited. There is an urgent unmet medical need to develop novel anti-TB agents to successfully combat emerging resistance. Recent progress has been achieved by the repurposing and redosing of known anti-TB drugs, but there are no new drug classes in clinical trials that act by novel mechanisms of action.The protein "Filamenting temperature-sensitive mutant Z" (FtsZ) is highly conserved among all types of bacteria, including Mycobacterium species that cause TB. It is an essential cell division protein with both GTPase and polymerisation activities. FtsZ subunits polymerise into protofilaments to form a dynamic ring-like structure called the Z-ring that functions as a scaffold for the assembly of the divisome, a multiprotein complex that causes contraction of the Z-ring, finally resulting in septum formation and cell division. Abnormalities in FtsZ block the Z-ring functions, leading to an elongated, filamentous phenotype, inhibition of cell division and subsequent cell death. Although FtsZ inhibitors have been identified, most are derived from natural products and there is a general lack of structural information, with many of the inhibitors classified as "false positives".We have purified M. tuberculosis (MTb) FtsZ in large amounts for biochemical, biophysical and structural studies. In collaboration with the Monash NMR screening facility, we identified 38 fragment hits against FtsZ. We established biophysical (DSF, MST) and biochemical (GTPase, right-angle scattering) assays to characterise its GTPase activity and polymerisation/depolymerisation dynamics. Uniquely, we have determined the crystal structure of FtsZ in complex with fragment hits and established their mechanism of action. We have evaluated the fragment binding sites with respect to fragment growth and merging and we are ready to initiate SAR-by-catalogue and custom-made optimisation of the hits to develop more potent analogues.In this project we aim to develop and characterise potent inhibitors of MTb FtsZ as a new class of antibiotic for the treatment of tuberculosis infections. We anticipate that such compounds will be a welcome addition to the treatment options available for TB and its drug-resistant variants. This collaborative drug discovery project addresses a clear unmet medical need. Successful completion of this project will underpin a broader collaborative drug discovery program including other UCL partners.