A structure-based mechanism for Arf1-dependent recruitment of coatomer to membranes.
Budding of COPI-coated vesicles from Golgi membranes requires an Arf family G protein and the coatomer complex recruited from cytosol. Arf is also required with coatomer-related clathrin adaptor complexes to bud vesicles from the trans-Golgi network and endosomal compartments. To understand the structural basis for Arf-dependent recruitment of a vesicular coat to the membrane, we determined the structure of Arf1 bound to the γζ-COP subcomplex of coatomer. Structure-guided biochemical analysis reveals that a second Arf1-GTP molecule binds to βδ-COP at a site common to the γ- and β-COP subunits. The Arf1-binding sites on coatomer are spatially related to PtdIns4,5P(2)-binding sites on the endocytic AP2 complex, providing evidence that the orientation of membrane binding is general for this class of vesicular coat proteins. A bivalent GTP-dependent binding mode has implications for the dynamics of coatomer interaction with the Golgi and for the selection of cargo molecules.
Howard Hughes Medical Institute and the Structural Biology Program, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA.
Xinchao
X
Yu
Marianna
M
Breitman
Jonathan
J
Goldberg
D020823:ADP-Ribosylation Factor 1 / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D022181:COP-Coated Vesicles / Q000737:chemistry / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism; D008958:Models, Molecular; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D016415:Sequence Alignment
D029701:Saccharomyces cerevisiae Proteins; D006160:Guanosine Triphosphate; D020823:ADP-Ribosylation Factor 1