金属离子依赖性蛋白磷酸酶PPM1K的催化机制、底物特异性和功能研究

金属离子依赖性蛋白磷酸酶PPM1K是体内代谢活动的重要调控因子，其突变与枫糖尿病和２型糖尿病密切相关。PPM1K不仅通过去磷酸化侧链酮酸脱氢酶复合物(BCKD)来促进侧链酮酸在体内的降解；还调控高糖介导的胰岛素分泌等多种代谢过程。理解PPM1K的催化机制、激活原理、底物特异性以及其调控代谢活动的机制，既是目前的研究热点也有重要科学意义。我们最近初步分析了金属离子介导的PPM1K对底物的催化机制，探索了BCKD-E2α对PPM1K的激活原理，明确了PPM1K对胰岛素分泌的关键节点KATP通道失活的作用。基于这些研究基础，本课题将联合分子与细胞生物学方法，应用多种酶学和结构生物学手段，阐明PPM1K的催化和激活原理、底物选择性和对胰岛素分泌的调控机制。进一步，基于PPM1K的底物选择性，我们还将联合生物信息学和新发展的PPM1K底物陷阱技术，发现PPM1K在代谢活动中的未知底物。

The metal dependent protein phosphatase PPM1K is an important regulator of cell metabolism. The mutations of PPM1K were associated with maple syrup urine disease （MSUD） and type 2 diabetes. In vivo, PPM1K not only promotes the degradation of the branched-chain amino acids (BCAA) through the dephosphorylation of the branched-chain alpha-ketoacid dehydrogenase complexes, but also regulates multiple metabolism processes, such as insulin secretion. Therefore, elucidation of the catalytic mechanism and function of PPM1K has great scientific value. Recently, we have accumulated preliminary data for the catalytic property of the PPM1K、the activation of the PPM1K by BCKD-E2α and the potentail role of the PPM1K in the regulation of KATP channel. We proposed investigate the detailed molecular mechanism underlying the catalysis and activation of the PPM1K、 the substrate specificity of the PPM1K and the role of PPM1K in regulation of the insulin secretion, by combined biochemical、enzymologic and structural methods. Moreover, we are going to identify the unknown substrate of PPM1K in physiological or pathological contexts.