title: Structural basis for recruitment of RILP by small GTPase Rab7.
abstract: Rab7 regulates vesicle traffic from early to late endosomes, and from late endosomes to lysosomes. The crystal structure of Rab7-GTP in complex with the Rab7 binding domain of RILP reveals that Rab7 interacts with RILP specifically via two distinct areas, with the first one involving the switch and interswitch regions and the second one consisting of RabSF1 and RabSF4. Disruption of these interactions by mutations abrogates late endosomal/lysosomal targeting of Rab7 and RILP. The Rab7 binding domain of RILP forms a coiled-coil homodimer with two symmetric surfaces to interact with two separate Rab7-GTP molecules, forming a dyad configuration of Rab7-RILP(2)-Rab7. Mutations that disrupt RILP dimerization also abolish its interactions with Rab7-GTP and late endosomal/lysosomal targeting, suggesting that the dimeric form of RILP is a functional unit. Structural comparison suggests that the combined use of RabSF1 and RabSF4 with the switch regions may be a general mode of action for most Rab proteins in regulating membrane trafficking.
authors.affiliation: Laboratory of Macromolecular Structure, Institute of Molecular and Cell Biology, Proteos, Singapore.
authors.forename: Mousheng
authors.initials: M
authors.lastname: Wu
authors.forename: Tuanlao
authors.initials: T
authors.lastname: Wang
authors.forename: Eva
authors.initials: E
authors.lastname: Loh
authors.forename: Wanjin
authors.initials: W
authors.lastname: Hong
authors.forename: Haiwei
authors.initials: H
authors.lastname: Song
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018360:Crystallography, X-Ray; D019281:Dimerization; D011992:Endosomes / Q000378:metabolism; D006801:Humans; D008247:Lysosomes / Q000378:metabolism; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D016415:Sequence Alignment; D022161:Transport Vesicles / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D020691:rab GTP-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000090802:rab7 GTP-Binding Proteins
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; C423317:RILP protein, human; C498920:Rilp protein, mouse; D000090802:rab7 GTP-Binding Proteins; C000716463:rab7 GTP-binding proteins, human; C000716465:rab7 GTP-binding proteins, mouse; D020691:rab GTP-Binding Proteins