结核分枝杆菌RbpA转录调控及在利福平耐药中的功能研究

结核分枝杆菌是引起结核病的重要病原细菌，随着现有抗结核药物的长期使用，耐药菌株的出现给结核的防治提出了新的挑战，耐药机理的研究一直是研究者热点关注的问题。利福平是重要的一线抗结核药物，其作用靶标为RNA聚合酶(RNAP)，利福平耐药的主要原因是RNAP的突变及活性调控。RbpA是一种新发现的RNAP活性调控蛋白，其表达受利福平诱导，且该蛋白的过表达能增强细菌对利福平的耐药性，但有关RbpA表达调控及在利福平耐药中的作用机理还未有清楚阐释。本项目将系统鉴定结核分枝杆菌RbpA的转录调控蛋白，探讨其调控细节，揭示RbpA受利福平诱导表达过程，并分析RbpA对RNAP活性调控的作用机制，最终从基因表达与RNAP调控的角度阐释结核分枝杆菌利福平耐药新机理。由于结核分枝杆菌RbpA是必须蛋白，且仅存在于放线菌，具备药物作用靶点的基本特征，本项目的开展将为RbpA作为新的抗结核药物靶点奠定基础。

Mycobacterium tuberculosis is one of the most successful human pathogens able to persist in drug-resistant state in the host for years. As reported by the World Health Organization that M. tuberculosis infects almost one third of the world population and continue to kill about 1.5 million people each year. Multiplication of the multi-drug resistant forms of the tuberculosis during the last decades raises a serious threat for public health worldwide. Thus, development of new anti-tuberculosis therapeutic strategies is essential task and necessitates the mechanistic studies of the resistance mechanisms and the new drug targets. Rifampicin, the antibiotic targeting bacterial RNA polymerase (RNAP), still remains the first-line drug used to cure tuberculosis infection. However, bacteria have developed multiple mechanisms to escape from the antibiotic treatment. Most of these mechanisms, such like mutations in the drug target, activation of the stress-response and switch to the persistent state are linked to the regulation of gene transcription. RbpA is a 14 kDa RNAP-binding protein that was reported to be involved in rifampicin tolerance, because overexpression of RbpA in Mycobacterium was shown to decrease its sensitivity to rifampicin, and expression of the rbpA gene was reported to be induced during the rifampicin treatment. Regarding these proofs, mechanism(s) about the role(s) of RbpA in rifampicin tolerance is not clear. Transcription of rbpA in presence of rifampicin is very important for its role in rifampicin tolerance, but its transcription regulation has never been studied yet. In this project, we suppose to identify the regulators that involved in rbpA regulation in M. tuberculosis and investigate the mechanism(s) for the rifampicin-induced rbpA transcription. Effects of RbpA to M. tuberculosis RNAP activity will also be studied to show the details for the role(s) of RbpA in RNAP activity regulation and rifampicn tolerance. The final goal of this project is to show a new mechanism for rifampicin tolerance in aspect of gene transcription regulation. RbpA is essential for M. tuberculosis and specific to Actinomycetes. For these, RbpA is a potential target for new anti-tuberculosis drug development. Our project will greatly promote this process.