标题：Crystal structure and catalytic activity of the PPM1K N94K mutant
作者：Dolatabad, Meisam Rostaminasab; Guo, Lu-lu; Xiao, Peng; Zhu, Zhongliang; He, Qing-tao; Yang, Du-xiao; Qu, Chang-xiu; Guo, Sheng-chao; 更多 作者机构：[Dolatabad, Meisam Rostaminasab; Guo, Lu-lu; Xiao, Peng; He, Qing-tao; Yang, Du-xiao; Qu, Chang-xiu; Guo, Sheng-chao; Fu, Xiao-lei; Li, Rui-rui; Ge, L 更多
通讯作者：Zhang, PJ;Sun, JP;Sun, JP
通讯作者地址：[Zhang, PJ]Shandong Univ, Sch Basic Med Sci, Dept Biochem & Mol Biol, 44 Wenhua Xi Rd, Jinan 250012, Shandong, Peoples R China;[Sun, JP]Shandong Univ, 更多
来源：JOURNAL OF NEUROCHEMISTRY
关键词：active site; crystal structure; phosphatase activity; protein; phosphatase Mg2+/Mn2+-dependent 1K; single nucleotide polymorphisms;; third metal ion
摘要：Protein Phosphatase Mg2+/Mn2+-Dependent 1K (PPM1K),also named as PP2Cm or branched-chain alpha-ketoacid dehydrogenase complex phosphatase, is a member of the metal-dependent phosphatase family and an important metabolic regulator. Single nucleotide polymorphisms (SNPs) in PPM1K contributing to protein functional defects have been found to be associated with numerous human diseases, such as cardiovascular disease, maple syrup urine disease, type 2 diabetes, and neurological disease. PPM1K N94K is an identified missense mutant produced by one of the SNPs in the human PPM1K coding sequence. However, the effects of the N94K mutant on its activity and structural property have not been defined. Here, we performed a detailed enzymological study using steady-state kinetics in the presence of pNPP or phospho-peptide substrates and crystallographic analyses of the wild-type and N94K PPM1K. The PPM1K-N94K significantly impaired its Mg2+-dependent catalytic activity and structural analysis demonstrated that the N94K mutation induced a conformational change in the key residue in coordinating the Mg2+ in the active site. Specifically, three Mg2+ were located in the active site of the PPM1K N94K instead of two Mg2+ in the PPM1K wild type. Therefore, our results provide a structure basis for the metal ion-dependent PPM1K-N94K phosphatase activity.