Membrane curvature induced by Arf1-GTP is essential for vesicle formation

• DOI: 10.1073/pnas.0805182105
• Publication Date: 2008-08-09T01:07:09Z
• Authors: Rainer Beck; Zhe Sun; Frank Adolf; Chistoph Rutz; Jochen Bassler; Klemens Wild; Irmgard Sinning; Ed Hurt; Britta Brügger; Julien Béthune; Felix Wieland
• Keywords: Models, Molecular; 0301 basic medicine; Golgi Apparatus; Intracellular Membranes; Lipid Metabolism; Models, Biological; Rats; 03 medical and health sciences; Liposomes; Animals; Humans; ADP-Ribosylation Factor 1; Guanosine Triphosphate; Protein Structure, Quaternary; Dimerization; HeLa Cells; Protein Binding

The GTPase Arf1 is considered as a molecular switch that regulates binding and release of coat proteins that polymerize on membranes to form transport vesicles. Here, we show that Arf1-GTP induces positive membrane curvature and find that the small GTPase can dimerize dependent on GTP. Investigating a possible link between Arf dimerization and curvature formation, we isolated an Arf1 mutant that cannot dimerize. Although it was capable of exerting the classical role of Arf1 as a coat receptor, it could not mediate the formation of COPI vesicles from Golgi-membranes and was lethal when expressed in yeast. Strikingly, this mutant was not able to deform membranes, suggesting that GTP-induced dimerization of Arf1 is a critical step inducing membrane curvature during the formation of coated vesicles.