title: Scission of COPI and COPII vesicles is independent of GTP hydrolysis.
abstract: Intracellular transport and maintenance of the endomembrane system in eukaryotes depends on formation and fusion of vesicular carriers. A seeming discrepancy exists in the literature about the basic mechanism in the scission of transport vesicles that depend on GTP-binding proteins. Some reports describe that the scission of COP-coated vesicles is dependent on GTP hydrolysis, whereas others found that GTP hydrolysis is not required. In order to investigate this pivotal mechanism in vesicle formation, we analyzed formation of COPI- and COPII-coated vesicles utilizing semi-intact cells. The small GTPases Sar1 and Arf1 together with their corresponding coat proteins, the Sec23/24 and Sec13/31 complexes for COPII and coatomer for COPI vesicles were required and sufficient to drive vesicle formation. Both types of vesicles were efficiently generated when GTP hydrolysis was blocked either by utilizing the poorly hydrolyzable GTP analogs GTPγS and GMP-PNP, or with constitutively active mutants of the small GTPases. Thus, GTP hydrolysis is not required for the formation and release of COP vesicles.
authors.affiliation: Heidelberg University Biochemistry Center, University of Heidelberg, Im Neuenheimer Feld 328, D-69120, Heidelberg, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Adolf
authors.forename: Alexia
authors.initials: A
authors.lastname: Herrmann
authors.forename: Andrea
authors.initials: A
authors.lastname: Hellwig
authors.forename: Rainer
authors.initials: R
authors.lastname: Beck
authors.forename: Britta
authors.initials: B
authors.lastname: Brügger
authors.forename: Felix T
authors.initials: FT
authors.lastname: Wieland
mesh_terms: D020823:ADP-Ribosylation Factor 1 / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D022181:COP-Coated Vesicles / Q000378:metabolism*; D006224:Cricetinae; D006160:Guanosine Triphosphate / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D006868:Hydrolysis; D009154:Mutation; D033921:Vesicular Transport Proteins / Q000378:metabolism*
chemical_list: C530638:SEC24A protein, human; C507455:SEC31A protein, human; D033921:Vesicular Transport Proteins; D006160:Guanosine Triphosphate; D020823:ADP-Ribosylation Factor 1
keywords: membrane fission; small GTPases; vesicular transport