title: Epsin N-terminal Homology Domain (ENTH) Activity as a Function of Membrane Tension.
abstract: The epsin N-terminal homology domain (ENTH) is a major player in clathrin-mediated endocytosis. To investigate the influence of initial membrane tension on ENTH binding and activity, we established a bilayer system based on adhered giant unilamellar vesicles (GUVs) to be able to control and adjust the membrane tension σ covering a broad regime. The shape of each individual adhered GUV as well as its adhesion area was monitored by spinning disc confocal laser microscopy. Control of σ in a range of 0.08-1.02 mN/m was achieved by altering the Mg(2+) concentration in solution, which changes the surface adhesion energy per unit area of the GUVs. Specific binding of ENTH to phosphatidylinositol 4,5-bisphosphate leads to a substantial increase in adhesion area of the sessile GUV. At low tension (<0.1 mN/m) binding of ENTH can induce tubular structures, whereas at higher membrane tension the ENTH interaction deflates the sessile GUV and thereby increases the adhesion area. The increase in adhesion area is mainly attributed to a decrease in the area compressibility modulus KA We propose that the insertion of the ENTH helix-0 into the membrane is largely responsible for the observed decrease in KA, which is supported by the observation that the mutant ENTH L6E shows a reduced increase in adhesion area. These results demonstrate that even in the absence of tubule formation, the area compressibility modulus and, as such, the bending rigidity of the membrane is considerably reduced upon ENTH binding. This renders membrane bending and tubule formation energetically less costly.
authors.affiliation: From the Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstrasse 2, 37077 Göttingen, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Gleisner
authors.affiliation: Department of Cellular Biochemistry, University of Göttingen, Humboldtallee 23, 37073 Göttingen, Germany.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Kroppen
authors.affiliation: From the Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstrasse 2, 37077 Göttingen, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Fricke
authors.affiliation: From the Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstrasse 2, 37077 Göttingen, Germany.
authors.forename: Nelli
authors.initials: N
authors.lastname: Teske
authors.affiliation: Institute of Physical Chemistry, University of Göttingen, Tammannstrasse 6, 37077 Göttingen, Germany, and.
authors.forename: Torben-Tobias
authors.initials: TT
authors.lastname: Kliesch
authors.affiliation: Institute of Physical Chemistry, University of Göttingen, Tammannstrasse 6, 37077 Göttingen, Germany, and Göttingen Center for Molecular Biosciences, 37077 Göttingen, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Janshoff
authors.affiliation: Department of Cellular Biochemistry, University of Göttingen, Humboldtallee 23, 37073 Göttingen, Germany, European Neuroscience Institute, 37073 Göttingen, Germany, michael.meinecke@med.uni-goettingen.de.
authors.forename: Michael
authors.initials: M
authors.lastname: Meinecke
authors.affiliation: From the Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstrasse 2, 37077 Göttingen, Germany, Göttingen Center for Molecular Biosciences, 37077 Göttingen, Germany csteine@gwdg.de.
authors.forename: Claudia
authors.initials: C
authors.lastname: Steinem
mesh_terms: D033942:Adaptor Proteins, Vesicular Transport / Q000737:chemistry*; D006801:Humans; D000072417:Protein Domains; D017433:Protein Structure, Secondary; D013500:Surface Tension; D053835:Unilamellar Liposomes / Q000737:chemistry*
chemical_list: D033942:Adaptor Proteins, Vesicular Transport; D053835:Unilamellar Liposomes; C114154:epsin
keywords: endocytosis; fluorescence; lipid vesicle; lipid-protein interaction; membrane protein