title: Structural perturbations in human ADP ribosylation factor-1 accompanying the binding of phosphatidylinositides.
abstract: ADP ribosylation factors (Arfs) are members of a family of Ras-related GTPases that regulate a wide variety of intracellular signaling pathways, including the regulation of membrane traffic and organelle morphology. Arfs perform these functions through interactions with Arf-specific guanine nucleotide exchange factors (GEFs), GTPase activating proteins (GAPs), and effectors. Signaling phosphatidylinositides, most commonly phosphatidylinositol (4,5)-bisphosphate (PI(4,5)P(2)) or phosphatidylinositol (3,4,5)-trisphosphate (PI(3,4,5)P(3)), have been shown previously to regulate the activities of a number of these regulators and effectors of Arf. The ability of Arf itself to bind these same phosphatidylinositides also has been reported previously, though without much structural detail. We investigated the ability of human Arf1.GDP (Arf1.GDP) to bind myo-inositol (1,4,5)-trisphosphate (I(1,4,5)P(3)), the soluble headgroup for PI(4,5)P(2), and a short acyl-chain soluble PI(4,5)P(2) analogue using heteronuclear single quantum coherence (HSQC)-based NMR techniques. A patch of positive electrostatic potential on the surface of Arf1.GDP is identified as being directly involved in ligand binding, but structural and stability changes extending to the N-terminal helix and nucleotide-binding site of Arf1 are also documented. The identified binding site and the resultant structural changes are discussed in terms of a possible influence of phosphatidylinositides on the binding of Arf1 to Arf1-GEF and subsequent nucleotide release.
authors.affiliation: Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, Georgia 30602-4712, USA.
authors.forename: Ronald D
authors.initials: RD
authors.lastname: Seidel
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Amor
authors.forename: Richard A
authors.initials: RA
authors.lastname: Kahn
authors.forename: James H
authors.initials: JH
authors.lastname: Prestegard
mesh_terms: D020823:ADP-Ribosylation Factor 1 / Q000737:chemistry* / Q000378:metabolism*; D000494:Allosteric Regulation; D000595:Amino Acid Sequence; D001665:Binding Sites; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D008024:Ligands; D021962:Membrane Microdomains / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D010716:Phosphatidylinositols / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D020662:Guanine Nucleotide Exchange Factors; D008024:Ligands; D010716:Phosphatidylinositols; D011994:Recombinant Proteins; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; D020823:ADP-Ribosylation Factor 1