title: Osmotically-induced tension and the binding of N-BAR protein to lipid vesicles.
abstract: The binding affinity of a curvature-sensing protein domain (N-BAR) is measured as a function of applied osmotic stress while the membrane curvature is nearly constant. Varying the osmotic stress allows us to control membrane tension, which provides a probe of the mechanism of binding. We study the N-BAR domain of the Drosophila amphiphysin and monitor its binding on 50 nm-radius vesicles composed of 90 mol% DOPC and 10 mol% PIP. We find that the bound fraction of N-BAR is enhanced by a factor of approximately 6.5 when the tension increases from zero to 2.6 mN m(-1). This tension-induced response can be explained by the hydrophobic insertion mechanism. From the data we extract a hydrophobic domain area that is consistent with known structure. These results indicate that membrane stress and strain could play a major role in the previously reported curvature-affinity of N-BAR.
authors.affiliation: Department of Physics, University of Massachusetts Amherst, Hasbrouck Lab 411, 666 North Pleasant Street, Amherst, MA 01003, USA. Dinsmore@physics.umass.edu.
authors.forename: Jaime B
authors.initials: JB
authors.lastname: Hutchison
authors.affiliation: Department of Chemistry, University of Massachusetts Amherst, USA.
authors.forename: Aruni P K K
authors.initials: AP
authors.lastname: Karunanayake Mudiyanselage
authors.affiliation: Department of Chemistry, University of Massachusetts Amherst, USA.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Weis
authors.affiliation: Department of Physics, University of Massachusetts Amherst, Hasbrouck Lab 411, 666 North Pleasant Street, Amherst, MA 01003, USA. Dinsmore@physics.umass.edu.
authors.forename: Anthony D
authors.initials: AD
authors.lastname: Dinsmore
mesh_terms: D000818:Animals; D055592:Biophysical Phenomena; D004330:Drosophila / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins / Q000737:chemistry* / Q000378:metabolism*; D007700:Kinetics; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D009995:Osmosis; D011485:Protein Binding; D000072417:Protein Domains; D013572:Synaptic Vesicles / Q000737:chemistry / Q000378:metabolism*
chemical_list: D029721:Drosophila Proteins; D009419:Nerve Tissue Proteins; C075637:amphiphysin