微管去谷氨酰化酶CCP5的结构和功能研究

多聚谷氨酰化是一种广泛存在的微管蛋白翻译后修饰，能够调节微管与效应蛋白的结合，进而调控微管的功能。谷氨酰化修饰水平受到谷氨酰化酶和去谷氨酰化酶的共同调节，去谷氨酰化酶家族中只有CCP5可以特异性水解分支点γ连接的谷氨酸。研究发现CCP5与神经退行性病变、男性不育以及纤毛病等疾病的发生相关。但是相关的分子机制目前还不清楚。申请人前期已经进行了大量微管翻译后修饰相关蛋白的结构生物学研究。本项目拟结合结构生物学、生化和细胞生物学等综合研究CCP5对微管谷氨酰化水平及微管功能的调控机制，以及抑制剂调控CCP5活性的分子机制。首先获取CCP5及其与小分子抑制剂的复合物的高分辨率的晶体结构，然后在生化和细胞层面进行突变研究，建立CCP5活性的精确调控模型，揭示其水解分支点谷氨酸的分子机制。结合复合物结构分析和筛选，为抑制剂的优化指明方向，为CCP5的生物学功能及靶向CCP5的药物的研究提供结构基础。

Glutamylation is a widespread tubulin posttranslational modification enriched on stable microtubules of neuronal axons, mitotic spindles, centrioles, cilia and basal body. Essential effector proteins can read the tubulin glutamylation pattern to fine-tune the function of microtubule. Glutamylation levels in cells are regulated through the opposing actions of both TTLL (tubulin tyrosine ligase like family) and CCPs (cytosolic carboxypeptidases family). CCPs are deglutamylase enzyme involved in the removal of the polyglutamylation from tubulin reverse the function of TTLL family. CCPs consists of six members CCP1 to CCP6. However, only CCP5 can efficiently hydrolyze the branching γ-carboxyl–linked glutamate to finish the final step of removal of the polyglutamylation. Loss of CCP5 leads to dysregulation of tubulin glutamylation, which associates with neurodegeneration, male infertility, and ciliopathy. However, the molecular mechanism of CCP5's recognition and hydrolysis of branching point glutamate remains enigmatic. Thus, the dissection of the molecular mechanisms and a comprehensive understanding of the biological functions of tubulin deglutamylation by CCP5 will be important and of high interest..In this research, we will use structural biology-based methods to uncover the molecular mechanisms for the tubulin deglutamylation by CCP5. The soluble CCP5 has already been purified. Subsequent experiments are ongoing. This research is critical for understanding the biological functions of CCP5, which also provides the molecular basis for therapy against related diseases.