title: Structural basis of the intracellular sorting of the SNARE VAMP7 by the AP3 adaptor complex.
abstract: VAMP7 is involved in the fusion of late endocytic compartments with other membranes. One possible mechanism of VAMP7 delivery to these late compartments is via the AP3 trafficking adaptor. We show that the linker of the δ-adaptin subunit of AP3 binds the VAMP7 longin domain and determines the structure of their complex. Mutation of residues on both partners abolishes the interaction in vitro and in vivo. The binding of VAMP7 to δ-adaptin requires the VAMP7 SNARE motif to be engaged in SNARE complex formation and hence AP3 must transport VAMP7 when VAMP7 is part of a cis-SNARE complex. The absence of δ-adaptin causes destabilization of the AP3 complex in mouse mocha fibroblasts and mislocalization of VAMP7. The mislocalization can be rescued by transfection with wild-type δ-adaptin but not by δ-adaptin containing mutations that abolish VAMP7 binding, despite in all cases intact AP3 being present and LAMP1 trafficking being rescued.
authors.affiliation: Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK.
authors.forename: Helen M
authors.initials: HM
authors.lastname: Kent
authors.forename: Philip R
authors.initials: PR
authors.lastname: Evans
authors.forename: Ingmar B
authors.initials: IB
authors.lastname: Schäfer
authors.forename: Sally R
authors.initials: SR
authors.lastname: Gray
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Sanderson
authors.forename: J Paul
authors.initials: JP
authors.lastname: Luzio
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Peden
authors.forename: David J
authors.initials: DJ
authors.lastname: Owen
mesh_terms: D033963:Adaptor Protein Complex 3 / Q000378:metabolism*; D033981:Adaptor Protein Complex delta Subunits / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D018360:Crystallography, X-Ray; D004705:Endocytosis; D011992:Endosomes / Q000378:metabolism; D005347:Fibroblasts; D005434:Flow Cytometry; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000502:physiology*; D050683:R-SNARE Proteins / Q000378:metabolism*
chemical_list: D033963:Adaptor Protein Complex 3; D033981:Adaptor Protein Complex delta Subunits; D050683:R-SNARE Proteins; C496927:Sybl1 protein, mouse