title: Molecular Basis for Cooperative Binding of Anionic Phospholipids to the PH Domain of the Arf GAP ASAP1.
abstract: We have defined the molecular basis for association of the PH domain of the Arf GAP ASAP1 with phospholipid bilayers. Structures of the unliganded and dibutyryl PtdIns(4,5)P2-bound PH domain were solved. PtdIns(4,5)P2 made contact with both a canonical site (C site) and an atypical site (A site). We hypothesized cooperative binding of PtdIns(4,5)P2 to the C site and a nonspecific anionic phospholipid to the A site. PtdIns(4,5)P2 dependence of binding to large unilamellar vesicles and GAP activity was sigmoidal, consistent with cooperative sites. In contrast, PtdIns(4,5)P2 binding to the PH domain of PLC δ1 was hyperbolic. Mutation of amino acids in either the C or A site resulted in decreased PtdIns(4,5)P2-dependent binding to vesicles and decreased GAP activity. The results support the idea of cooperative phospholipid binding to the C and A sites of the PH domain of ASAP1. We propose that the mechanism underlies rapid switching between active and inactive ASAP1.
authors.affiliation: Laboratory of Cellular and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Xiaoying
authors.initials: X
authors.lastname: Jian
authors.affiliation: Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Wai-Kwan
authors.initials: WK
authors.lastname: Tang
authors.affiliation: Laboratory of Cellular and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Peng
authors.initials: P
authors.lastname: Zhai
authors.affiliation: Laboratory of Cellular and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Neeladri Sekhar
authors.initials: NS
authors.lastname: Roy
authors.affiliation: Laboratory of Cellular and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Ruibai
authors.initials: R
authors.lastname: Luo
authors.affiliation: Laboratory of Structural Biophysics, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: James M
authors.initials: JM
authors.lastname: Gruschus
authors.affiliation: Genetics Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Marielle E
authors.initials: ME
authors.lastname: Yohe
authors.affiliation: Laboratory of Cellular and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Pei-Wen
authors.initials: PW
authors.lastname: Chen
authors.affiliation: Structural Biophysics Laboratory, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Yifei
authors.initials: Y
authors.lastname: Li
authors.affiliation: Structural Biophysics Laboratory, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: R Andrew
authors.initials: RA
authors.lastname: Byrd
authors.affiliation: Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; Laboratory of Cell Biology, National Cancer Institute, Building 37, Room 2122, Bethesda, MD 20892, USA. Electronic address: dixia@helix.nih.gov.
authors.forename: Di
authors.initials: D
authors.lastname: Xia
authors.affiliation: Laboratory of Cellular and Molecular Biology, National Cancer Institute, National Institutes of Health, Building 37, Room 2042, Bethesda, MD 20892, USA. Electronic address: randazzp@mail.nih.gov.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Randazzo
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry* / Q000378:metabolism; D000595:Amino Acid Sequence; D001665:Binding Sites; D006801:Humans; D062105:Molecular Docking Simulation; D008969:Molecular Sequence Data; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding
chemical_list: C117891:ASAP1 protein, human; D048868:Adaptor Proteins, Signal Transducing; D019269:Phosphatidylinositol 4,5-Diphosphate