title: Quantifying Membrane Curvature Generation ofDrosophilaAmphiphysin N-BAR Domains.
abstract: Biological membrane functions are coupled to membrane curvature, the regulation of which often involves membrane-associated proteins. The membrane-binding N-terminal amphipathic helix-containing BIN/Amphiphysin/Rvs (N-BAR) domain of amphiphysin is implicated in curvature generation and maintenance. Improving the mechanistic understanding of membrane curvature regulation by N-BAR domains requires quantitative experimental characterization. We have measured tube pulling force modulation by the N-BAR domain of Drosophila amphiphysin (DA-N-BAR) bound to tubular membranes pulled from micropipette-aspirated giant vesicles. We observed that fluorescently-labeled DA-N-BAR showed significantly higher protein density on tubules compared to the connected low-curvature vesicle membrane. Furthermore, we found the equilibrium tube pulling force to be systematically dependent on the aqueous solution concentration of DA-N-BAR, thereby providing the first quantitative assessment of spontaneous curvature generation. At sufficiently high protein concentrations, pulled tubes required no external force to maintain mechanical equilibrium, in agreement with the qualitative spontaneous tubulation previously reported for amphiphysin.
authors.affiliation: University of Pennsylvania, Department of Chemistry.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Heinrich
authors.forename: Benjamin R
authors.initials: BR
authors.lastname: Capraro
authors.forename: Aiwei
authors.initials: A
authors.lastname: Tian
authors.forename: Jose M
authors.initials: JM
authors.lastname: Isas
authors.forename: Ralf
authors.initials: R
authors.lastname: Langen
authors.forename: Tobias
authors.initials: T
authors.lastname: Baumgart
keywords: GUV; curvature sensing; curvature sorting; membrane mechanics; pulling force