分枝杆菌CpsA蛋白的功能及其致病的分子机制研究

分枝杆菌CpsA蛋白属LCP(LytR-CpsA-Psr)家族蛋白，与细菌的细胞壁合成和致病性相关。我们及国外学者均发现分枝杆菌CpsA具有磷酸转移酶活性，且CpsA直接抑制细胞杀菌活性，促进细菌增殖。但其与宿主相互作用的蛋白及致病分子机制尚未完全明晰。国外近期发现CpsA可干扰宿主自噬通路中的LAP途径，我们发现其还可影响细胞的TNFα及NO杀伤通路。因此，我们提出分枝杆菌CpsA与宿主靶蛋白相互作用，除干扰细胞LAP的杀菌途径外，调节NO杀伤途径及TNFα信号通路也是其重要的致病机制的科学假设。本项目拟以海分枝杆菌为对象，利用分子生物学、细胞生物学、免疫学和蛋白组学等方法，及细胞和斑马鱼感染模型鉴定与CpsA相互作用的宿主蛋白及关键位点，阐明CpsA抑制宿主免疫反应的分子机制。本研究成果对于阐明CpsA作为免疫调节蛋白在分枝杆菌致病中的作用和揭示新的细菌和宿主相互作用机制具有重要意义。

Mycobacterial CpsA protein belongs to LCP family proteins and is related to cell wall synthesis as well as pathogenesis. Foreign scholars and us found that Mycobacterial CpsA protein bears an activity of phosphate transferase and is able to inhibit cell bactericidal activity to promote the proliferation of bacteria in the cell. But the interactional target proteins of CpsA and pathogenic molecular mechanisms are not illustrated completely. A recent discovery of CpsA by foreign investigators can interact with LAP pathway of host autophagy mechanism. on the other hand, our previous study found that CpsA can influence TNFα signal pathway and NO killing pathway as well. Therefore, we hypothesis that in addition to interfering with LAP pathway in the cell, regulating NO killing pathway and TNFa signaling pathway through the interaction between Mycobacterial CpsA protein and host target proteins is also a significant pathogenic mechanism interacts. By means of molecular biology, cell biology, immunology and proteomics research methods with macrophages and zebrafish infection model, we propose to identify the host protein and the key amino acid sites interacting with CpsA, to illuminate the molecular mechanism of immunoreaction inhibition by CpsA in Mycobacterium marinum. The research findings have significance to clarify the pathogenic role of CpsA in Mycobacterium marinum as an immunoregulator protein and reveal new interaction mechanism of bacteria and host.