结核分枝杆菌毒素-抗毒素家族MazEF-mt9参与耐药机制调控的研究

Pulmonary tuberculosis (TB) is a severe infectious disease caused by Mycobacterium tuberculosis (M. tb), and it seriously threatens the well-being of humankind. The wide spread of drug-resistant M. tb poses the biggest obstacle for the prevention and treatment of this disease, the occurrence of which is correlated with the formation of the persisters of M. tb in most cases..Toxin-antitoxin systems (TA systems) widely exist in bacteria, which are normally composed of a pair of molecules that antagonize each other. Toxins are usually endonucleases that act on mRNAs and rRNAs in order to exert their toxicities. M. tb has nine MazEF TA systems, and some of them have been proved to be directly associated with the genesis of persisters and drug-resistance of M. tb. Recently the MazF-mt9 toxin has been found to display endonuclease activities towards certain tRNAs. However, the unique substrate recognition mechanism of MazF, the relationship of the MazEF-mt9 to drug-resistance, its biochemical properties, and the regulation mechanism are completely unknown. In this study, we plan to establish the relationship of the MazEF-mt9 to M. tb drug-resistance and also seek to understand how the MazEF-mt9 system is regulated at the transcriptional/translational/post-translational levels. These studies not only help to elucidate the potential role and the molecular mechanism of MazEF-mt9 in the formation of drug-resistant M. tb persisters, but also offer potential novel means to anti-TB drug design. Therefore, our studies hold promise to both theoretical research as well as clinical applications.

肺结核病是由结核分枝杆菌引起的一种重大呼吸系统传染病，严重威胁人类健康，结核杆菌的耐药性是该病防治的最大障碍，较多情况下与持留菌的形成有关。毒素-抗毒素系统（TA系统）是细菌中广泛存在的、具有相互拮抗作用的分子对，毒素多为核酸内切酶，一般以内切mRNA或rRNA而发挥毒性。结核杆菌具有9个MazEF TA系统，其中一些系统已被证实与结核耐药性存在直接关系。近年来发现的MazF-mt9是唯一以tRNA为底物的MazF家族成员，但MazEF独特的底物识别机制、与耐药性的关系、生化性质及其所受调控作用几乎未见报道。本课题拟研究MazEF-mt9系统在结核杆菌耐药性中所起作用，及其在转录、翻译、翻译后水平受到的不同层次的调控，阐明MazEF-mt9介导的持留结核杆菌形成中的潜在作用及分子机制，为针对耐药结核杆菌药物的研发提供新思路，具有重要的理论与现实意义。

肺结核病是由结核分枝杆菌引起的一种重大呼吸系统传染病，严重威胁人类健康，结核杆菌的耐药性是该病防治的最大障碍，较多情况下与持留菌的形成有关。毒素-抗毒素系统（TA系统）是细菌中广泛存在的、具有相互拮抗作用的分子对，毒素多为核酸内切酶，一般以内切mRNA或rRNA而发挥毒性。结核杆菌具有9个MazEF TA系统，其中一些系统已被证实与结核耐药性存在直接关系。近年来发现的MazF-mt9是唯一以tRNA为底物的MazF家族成员，但MazEF独特的底物识别机制、与耐药性的关系、生化性质及其所受调控作用几乎未见报道。本项目确认了 MazEF-mt9 系统与结核杆菌耐药性之间的关系，发现mazEF-mt9 基因在转录水平、翻译后水平以水平受到不同层次及多元素的调控机制，揭示结核杆菌持留菌可能通过包括MazEF-mt9 在内的多个MazEF家族成员组成的网络系统介导其形成过程，并进行了相应系统的结构、生化及体内研究。本项目共发表论文3篇，其中SCI论文3篇，发表于 ACS infectious diseases (两篇) 和Toxin, 均为中科院二区期刊。解析了两个MazEF家族成员的毒素-抗毒素以及毒素-抗毒素多肽的多套复合物结构，其共晶结构和突变研究提供了详细的毒素底物识别的机制，为基于抗结核药物新靶点的设计提供了结构基础。同时，将MazF作为抗结核的靶点设计抗菌肽，如在MazF-mt9案例中，我们获得了具有不同的亲和力、极性和大小的候选肽，为探索结核病新药物靶点做出了有益的贡献，有助于在未来设计基于多肽的药物来对抗这种毒素及持留结核杆菌. 此研究结果的进一步深入，有望缓解结核病的无药可用情况，为治疗结核病提供新思路和理论依据。

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