COPI coat assembly occurs on liquid-disordered domains and the associated membrane deformations are limited by membrane tension.
Cytoplasmic coat proteins are required for cargo selection and budding of tubulovesicular transport intermediates that shuttle between intracellular compartments. To better understand the physical parameters governing coat assembly and coat-induced membrane deformation, we have reconstituted the Arf1-dependent assembly of the COPI coat on giant unilamellar vesicles by using fluorescently labeled Arf1 and coatomer. Membrane recruitment of Arf1-GTP occurs exclusively on disordered lipid domains and does not induce optically visible membrane deformation. In the presence of Arf1-GTP, coatomer self-assembles into weakly curved coats on membranes under high tension, while it induces extensive membrane deformation at low membrane tension. These deformations appear to have a composition different from the parental membrane because they are protected from phase transition. These findings suggest that the COPI coat is adapted to liquid disordered membrane domains where it could promote lipid sorting and that its mechanical effects can be tuned by membrane tension.
Manneville
Jean-Baptiste
JB
Unité Mixte de Recherche 144, Centre National de la Recherche Scientifique-Institut Curie, 26 rue d'Ulm, 75248 Paris Cedex 05, France.
Casella
Jean-François
JF
Ambroggio
Ernesto
E
Gounon
Pierre
P
Bertherat
Julien
J
Bassereau
Patricia
P
Cartaud
Jean
J
Antonny
Bruno
B
Goud
Bruno
B
D020823:ADP-Ribosylation Factor 1 / Q000378:metabolism; D000818:Animals; D022181:COP-Coated Vesicles / Q000502:physiology* / Q000648:ultrastructure; D002462:Cell Membrane / Q000502:physiology / Q000648:ultrastructure; D020755:Coat Protein Complex I / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011817:Rabbits; D053835:Unilamellar Liposomes / Q000378:metabolism
D020755:Coat Protein Complex I; D053835:Unilamellar Liposomes; D006160:Guanosine Triphosphate; D020823:ADP-Ribosylation Factor 1