title: Structural basis for the phosphorylation-regulated focal adhesion targeting of type Igamma phosphatidylinositol phosphate kinase (PIPKIgamma) by talin.
abstract: Phosphatidylinositol-4,5-bisphosphate (PIP2) is a key lipid messenger that regulates myriad diverse cellular signaling pathways. To ensure specificity in disparate cellular events, PIP2 must be localized to specific sub-cellular sites. At PIP2-regulated focal adhesion (FA) sites, such localization is in part mediated via the recruitment and activation of PIP2-producing enzyme, type Igamma phosphatidylinositol phosphate kinase (PIPKIgamma), by a phosphotyrosine binding (PTB) domain of talin. Transient phosphorylation of PIPKIgamma at Y644 regulates the interaction and efficient FA targeting of PIPKIgamma; however, the underlying structural basis remains elusive. We have determined the NMR structure of talin-1 PTB in complex with the Y644-phosphorylated PIPKIgamma fragment (WVpYSPLH). As compared to canonical PTB domains that typically recognize the NPXpY turn motif from a variety of signaling proteins, our structure displays an unusual non-NPXpY-based recognition mode for talin-1 PTB where K(357)RW in beta5 strand forms an antiparallel beta-sheet with the VpYS of PIPKIgamma. A specific electrostatic triad between K357/R358 of talin-1 PTB and the pY644 of PIPKIgamma was observed, which is consistent with the mutagenesis and isothermal calorimetry data. Combined with previous in vivo data, our results provide a framework for understanding how phosphorylation of Y644 in PIPKIgamma promotes its specific interaction with talin-1, leading to efficient local synthesis of PIP2 and dynamic regulation of integrin-mediated FA assembly.
authors.affiliation: Structural Biology Program, Lerner Research Institute, The Cleveland Clinic Foundation, Cleveland State University, OH 44195, USA.
authors.forename: Xiangming
authors.initials: X
authors.lastname: Kong
authors.forename: Xiaoxia
authors.initials: X
authors.lastname: Wang
authors.forename: Saurav
authors.initials: S
authors.lastname: Misra
authors.forename: Jun
authors.initials: J
authors.lastname: Qin
mesh_terms: D000818:Animals; D002151:Calorimetry; D022001:Focal Adhesions / Q000737:chemistry / Q000378:metabolism*; D051379:Mice; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000737:chemistry* / Q000378:metabolism; D019000:Phosphotyrosine / Q000378:metabolism; D011487:Protein Conformation; D016608:Talin / Q000737:chemistry* / Q000378:metabolism
chemical_list: D010446:Peptide Fragments; D019269:Phosphatidylinositol 4,5-Diphosphate; D016608:Talin; D019000:Phosphotyrosine; D017853:Phosphotransferases (Alcohol Group Acceptor)