title: Mechanism of substrate specificity of phosphatidylinositol phosphate kinases.
abstract: The phosphatidylinositol phosphate kinase (PIPK) family of enzymes is primarily responsible for converting singly phosphorylated phosphatidylinositol derivatives to phosphatidylinositol bisphosphates. As such, these kinases are central to many signaling and membrane trafficking processes in the eukaryotic cell. The three types of phosphatidylinositol phosphate kinases are homologous in sequence but differ in catalytic activities and biological functions. Type I and type II kinases generate phosphatidylinositol 4,5-bisphosphate from phosphatidylinositol 4-phosphate and phosphatidylinositol 5-phosphate, respectively, whereas the type III kinase produces phosphatidylinositol 3,5-bisphosphate from phosphatidylinositol 3-phosphate. Based on crystallographic analysis of the zebrafish type I kinase PIP5Kα, we identified a structural motif unique to the kinase family that serves to recognize the monophosphate on the substrate. Our data indicate that the complex pattern of substrate recognition and phosphorylation results from the interplay between the monophosphate binding site and the specificity loop: the specificity loop functions to recognize different orientations of the inositol ring, whereas residues flanking the phosphate binding Arg244 determine whether phosphatidylinositol 3-phosphate is exclusively bound and phosphorylated at the 5-position. This work provides a thorough picture of how PIPKs achieve their exquisite substrate specificity.
authors.affiliation: Department of Pharmacology, Yale School of Medicine, New Haven, CT 06520;
authors.forename: Yagmur
authors.initials: Y
authors.lastname: Muftuoglu
authors.affiliation: Department of Pharmacology, Yale School of Medicine, New Haven, CT 06520;
authors.forename: Yi
authors.initials: Y
authors.lastname: Xue
authors.affiliation: Department of Pharmacology, Yale School of Medicine, New Haven, CT 06520; Department of Neurosurgery and Institute of Neurosurgery, State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy, West China Hospital, West China Medical School, Sichuan University, Chengdu 610041, People's Republic of China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Gao
authors.affiliation: Department of Pharmacology, Yale School of Medicine, New Haven, CT 06520;
authors.forename: Dianqing
authors.initials: D
authors.lastname: Wu
authors.affiliation: Department of Pharmacology, Yale School of Medicine, New Haven, CT 06520; ya.ha@yale.edu.
authors.forename: Ya
authors.initials: Y
authors.lastname: Ha
mesh_terms: D000818:Animals; D001665:Binding Sites / Q000235:genetics; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D018129:Phosphatidylinositol Phosphates / Q000737:chemistry / Q000378:metabolism*; D010716:Phosphatidylinositols / Q000737:chemistry / Q000378:metabolism; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D000072417:Protein Domains; D013379:Substrate Specificity; D029961:Zebrafish Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols; D029961:Zebrafish Proteins; C055525:phosphatidylinositol 3-phosphate; D017853:Phosphotransferases (Alcohol Group Acceptor); C020077:1-phosphatidylinositol-4-phosphate 5-kinase
keywords: crystallography; lipid kinases; protein engineering; substrate specificity