微管蛋白去酪氨酸化与有丝分裂、神经系统发育、心肌细胞收缩等密切相关。VASH（VASH1/2）是主要的微管蛋白去酪氨酸酶，SVBP与VASH结合，调节其稳定性和活性。VASH2去酪氨酸酶活性在癌细胞转移中发挥重要作用。VASH是治疗微管去酪氨酸失调所致疾病的重要靶标。VASH的天然底物为α/β-tubulin及微管，其对微管具有底物偏好性，但分子机制不明。我们及其他课题组前期揭示VASH-SVBP的催化机理，但已有数据不能准确阐明其天然底物识别机制，也无法解释癌症患者的VASH2错义突变。本项目应用酶学、结构及细胞生物学等方法，研究VASH-SVBP与底物复合物的结构；探究微管其它翻译后修饰对VASH酶学性质的影响机制；鉴定VASH2促细胞迁移突变，并研究其对蛋白酶学与生化性质的影响。所得结果将揭示VASH-SVBP识别天然底物及底物偏好性的机理，为研究微管去酪氨酸失调所致疾病奠定基础。

Tubulin detyrosination has been closely related to mitosis, neurodevelopment, as well as cardiomyocyte contraction. Vasohibins (VASH1/2) are major enzymes for tubulin detyrosination. SVBP interacts with VASH, regulating its stability and activity. The tubulin detyrosinase activity of VASH2 plays a vital role in cancer cell migration and metastasis. VASH-SVBP is an important target for treating diseases associated with the disorders of tubulin detyrosination. The natural substrates of VASH are α/β-tubulin heterodimer and microtubules, and VASH-SVBP displays substrate preference towards α-tubulin present in microtubules compared with its unpolymerized form. However, the molecular mechanism underlying this preference still remains elusive. We and other groups have revealed the catalytic mechanism of VASH-SVBP recently, but the existing data could not illuminate its recognition mechanism for natural substrates and fail to explain the VASH2 missense mutations of cancer patients. By using the approaches of enzymology, structural biology and cell biology, we propose to study the complex structures of VASH-SVBP-α/β-tubulin and VASH-SVBP-microtubule, discuss the impact of enzymology on VASH exerted by other post-translational modifications of tubulin. Meanwhile, our project intends to identify the VASH2 mutations that promote cell migration, seeking to discover the effects of these mutations on the enzymatic and biochemical properties of VASH2. The results obtained will reveal the mechanism of natural substrate recognition and substrate preference of VASH-SVBP, thus laying the foundation for further studies into diseases associated with the disorders of tubulin detyrosination.