title: Multivalent Rab interactions determine tether-mediated membrane fusion.
abstract: Membrane fusion at endomembranes requires cross-talk between Rab GTPases and tethers to drive SNARE-mediated lipid bilayer mixing. Several tethers have multiple Rab-binding sites with largely untested function. Here we dissected the lysosomal HOPS complex as a tethering complex with just two binding sites for the Rab7-like Ypt7 protein to determine their relevance for fusion. Using tethering and fusion assays combined with HOPS mutants, we show that HOPS-dependent fusion requires both Rab-binding sites, with Vps39 being the stronger Ypt7 interactor than Vps41. The intrinsic amphipathic lipid packaging sensor (ALPS) motif within HOPS Vps41, a target of the vacuolar kinase Yck3, is dispensable for tethering and fusion but can affect tethering if phosphorylated. In combination, our data demonstrate that a multivalent tethering complex uses its two Rab bindings to determine the place of SNARE assembly and thus fusion at endomembranes.
authors.affiliation: Biochemistry Section, Department of Biology/Chemistry, University of Osnabrück, 49076 Osnabrück, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Lürick
authors.affiliation: Biochemistry Section, Department of Biology/Chemistry, University of Osnabrück, 49076 Osnabrück, Germany.
authors.forename: Jieqiong
authors.initials: J
authors.lastname: Gao
authors.affiliation: Department of Physical Biochemistry, Max-Planck Institute of Molecular Physiology; 44227 Dortmund, Germany.
authors.forename: Anne
authors.initials: A
authors.lastname: Kuhlee
authors.affiliation: Biochemistry Section, Department of Biology/Chemistry, University of Osnabrück, 49076 Osnabrück, Germany.
authors.forename: Erdal
authors.initials: E
authors.lastname: Yavavli
authors.affiliation: Biochemistry Section, Department of Biology/Chemistry, University of Osnabrück, 49076 Osnabrück, Germany.
authors.forename: Lars
authors.initials: L
authors.lastname: Langemeyer
authors.affiliation: Biochemistry Section, Department of Biology/Chemistry, University of Osnabrück, 49076 Osnabrück, Germany.
authors.forename: Angela
authors.initials: A
authors.lastname: Perz
authors.affiliation: Department of Physical Biochemistry, Max-Planck Institute of Molecular Physiology; 44227 Dortmund, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Raunser
authors.affiliation: Biochemistry Section, Department of Biology/Chemistry, University of Osnabrück, 49076 Osnabrück, Germany cu@uos.de.
authors.forename: Christian
authors.initials: C
authors.lastname: Ungermann
mesh_terms: D001665:Binding Sites; D011992:Endosomes / Q000378:metabolism; D008561:Membrane Fusion / Q000502:physiology*; D010766:Phosphorylation; D011485:Protein Binding; D021381:Protein Transport / Q000502:physiology; D050600:SNARE Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism* / Q000502:physiology; D014617:Vacuoles / Q000378:metabolism; D033921:Vesicular Transport Proteins / Q000378:metabolism; D020691:rab GTP-Binding Proteins / Q000378:metabolism* / Q000502:physiology
chemical_list: D050600:SNARE Proteins; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins; C079005:YPT7 protein, S cerevisiae; D020691:rab GTP-Binding Proteins