title: Tubulation by amphiphysin requires concentration-dependent switching from wedging to scaffolding.
abstract: BAR proteins are involved in a variety of membrane remodeling events but how they can mold membranes into different shapes remains poorly understood. Using electron paramagnetic resonance, we find that vesicle binding of the N-BAR protein amphiphysin is predominantly mediated by the shallow insertion of amphipathic N-terminal helices. In contrast, the interaction with tubes involves deeply inserted N-terminal helices together with the concave surface of the BAR domain, which acts as a scaffold. Combined with the observed concentration dependence of tubulation and BAR domain scaffolding, the data indicate that initial membrane deformations and vesicle binding are mediated by insertion of amphipathic helical wedges, while tubulation requires high protein densities at which oligomeric BAR domain scaffolds form. In addition, we identify a pocket of residues on the concave surface of the BAR domain that insert deeply into tube membrane. Interestingly, this pocket harbors a number of disease mutants in the homologous amphiphysin 2.
authors: Zilkha Neurogenetic Institute, University of Southern California, 1501 San Pablo Street, Los Angeles, CA 90033, USA.
authors: J Mario
authors: JM
authors: Isas
authors: Zilkha Neurogenetic Institute, University of Southern California, 1501 San Pablo Street, Los Angeles, CA 90033, USA.
authors: Mark R
authors: MR
authors: Ambroso
authors: Zilkha Neurogenetic Institute, University of Southern California, 1501 San Pablo Street, Los Angeles, CA 90033, USA.
authors: Prabhavati B
authors: PB
authors: Hegde
authors: Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089-2910, USA.
authors: Jennifer
authors: J
authors: Langen
authors: Zilkha Neurogenetic Institute, University of Southern California, 1501 San Pablo Street, Los Angeles, CA 90033, USA. Electronic address: langen@usc.edu.
authors: Ralf
authors: R
authors: Langen
mesh_terms: D000818:Animals; D001665:Binding Sites; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D018360:Crystallography, X-Ray; D004330:Drosophila / Q000737:chemistry / Q000378:metabolism*; D029721:Drosophila Proteins / Q000737:chemistry / Q000378:metabolism; D058635:Lipid-Linked Proteins / Q000737:chemistry*; D008954:Models, Biological; D008958:Models, Molecular; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D017433:Protein Structure, Secondary
chemical_list: D029721:Drosophila Proteins; D058635:Lipid-Linked Proteins; D009419:Nerve Tissue Proteins; C075637:amphiphysin