title: Structural basis for ARF1-mediated recruitment of ARHGAP21 to Golgi membranes.
abstract: ARHGAP21 is a Rho family GTPase-activating protein (RhoGAP) that controls the Arp2/3 complex and F-actin dynamics at the Golgi complex by regulating the activity of the small GTPase Cdc42. ARHGAP21 is recruited to the Golgi by binding to another small GTPase, ARF1. Here, we present the crystal structure of the activated GTP-bound form of ARF1 in a complex with the Arf-binding domain (ArfBD) of ARHGAP21 at 2.1 A resolution. We show that ArfBD comprises a PH domain adjoining a C-terminal alpha helix, and that ARF1 interacts with both of these structural motifs through its switch regions and triggers structural rearrangement of the PH domain. We used site-directed mutagenesis to confirm that both the PH domain and the helical motif are essential for the binding of ArfBD to ARF1 and for its recruitment to the Golgi. Our data demonstrate that two well-known small GTPase-binding motifs, the PH domain and the alpha helical motif, can combine to create a novel mode of binding to Arfs.
authors.affiliation: Centre de Recherche, UMR 144, Institut Curie, 26 rue d'Ulm, 75248 Paris Cedex 05, France.
authors.forename: Julie
authors.initials: J
authors.lastname: Ménétrey
authors.forename: Mylène
authors.initials: M
authors.lastname: Perderiset
authors.forename: Jérome
authors.initials: J
authors.lastname: Cicolari
authors.forename: Thierry
authors.initials: T
authors.lastname: Dubois
authors.forename: Nadia
authors.initials: N
authors.lastname: Elkhatib
authors.forename: Fatima
authors.initials: F
authors.lastname: El Khadali
authors.forename: Michel
authors.initials: M
authors.lastname: Franco
authors.forename: Philippe
authors.initials: P
authors.lastname: Chavrier
authors.forename: Anne
authors.initials: A
authors.lastname: Houdusse
mesh_terms: D020823:ADP-Ribosylation Factor 1 / Q000737:chemistry* / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D018360:Crystallography, X-Ray; D020690:GTPase-Activating Proteins / Q000737:chemistry* / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D007425:Intracellular Membranes / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D010716:Phosphatidylinositols / Q000378:metabolism; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
chemical_list: C459590:ARHGAP21 protein, human; D020690:GTPase-Activating Proteins; D010716:Phosphatidylinositols; D020823:ADP-Ribosylation Factor 1