title: Dual role of BAR domain-containing proteins in regulating vesicle release catalyzed by the GTPase, dynamin-2.
abstract: Dynamin-2 (Dyn2) is ubiquitously expressed and catalyzes membrane fission during clathrin-mediated endocytosis in nonneuronal cells. We have previously shown that Dyn2 inefficiently generates membrane curvature and only mediates fission of highly curved membranes. This led to the hypothesis that other endocytic accessory proteins (EAPs) generate curvature needed to sculpt a sufficiently narrow neck to trigger Dyn2 assembly and fission. Candidates for this activity are EAPs that bind to the dynamin proline/arginine-rich domain (PRD) through their SH3 (src homology-3) domains and also encode curvature-generating BAR (Bin/Amphiphysin/Rvs) domains. We show that at low concentrations, amphiphysin and endophilin, but not SNX9 or the curvature-generating epsin N-terminal homology (ENTH) domain, are able to generate tubules from planar membrane templates and to synergize with Dyn2ΔPRD to catalyze vesicle release. Unexpectedly, SH3-PRD interactions were inhibitory and reciprocally regulate scaffold assembly. Of the three proteins studied, only full-length amphiphysin functions synergistically with full-length Dyn2 to catalyze vesicle release. The differential activity of these proteins correlates with the relative potency of their positive, curvature-generating activity, and the negative regulatory effects mediated by SH3 domain interactions. Our findings reveal opportunities for the spatio-temporal coordination of membrane curvature generation, dynamin assembly, and fission during clathrin-mediated endocytosis.
authors.affiliation: From the Department of Cell Biology, The Scripps Research Institute, La Jolla, California 92037.
authors.forename: Sylvia
authors.initials: S
authors.lastname: Neumann
authors.affiliation: From the Department of Cell Biology, The Scripps Research Institute, La Jolla, California 92037. Electronic address: sandra.schmid@utsouthwestern.edu.
authors.forename: Sandra L
authors.initials: SL
authors.lastname: Schmid
mesh_terms: D002384:Catalysis; D002462:Cell Membrane / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D034285:Dynamin II / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004705:Endocytosis / Q000502:physiology; D006801:Humans; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018909:src Homology Domains
chemical_list: D009419:Nerve Tissue Proteins; C075637:amphiphysin; D034285:Dynamin II
keywords: BAR Domain; Dynamin; ENTH Domain; Endocytosis; Membrane Curvature; Membrane Fission; Membrane Trafficking; Membrane Transport; Molecular Cell Biology; Vesicles