Membrane recruitment of the cargo-selective retromer subcomplex is catalysed by the small GTPase Rab7 and inhibited by the Rab-GAP TBC1D5.
Retromer is a membrane-associated heteropentameric coat complex that functions in the endosome-to-Golgi retrieval of the cation-independent mannose-6-phosphate receptor, the Wntless protein and other membrane proteins of physiological significance. Retromer comprises two functional subcomplexes: the cargo-selective subcomplex is a trimer of the VPS35, VPS29, VPS26 proteins, whereas the sorting nexin proteins, Snx1 and Snx2 function to tubulate the endosomal membrane. Unlike the sorting nexins, which contain PtdIns3P-binding PX domains, the cargo-selective VPS35/29/26 complex has no lipid-binding domains and its recruitment to the endosomal membrane remains mechanistically uncharacterised. In this study we show that the VPS35/29/26 complex interacts with the small GTPase Rab7 and requires Rab7 for its recruitment to the endosome. We show that the Rab7K157N mutant that causes the peripheral neuropathy, Charcot-Marie-Tooth disease, does not interact with the VPS35/29/26 complex, resulting in a weakened association with the membrane. We have also identified a novel retromer-interacting protein, TBC1D5, which is a member of the Rab GAP family of proteins that negatively regulates VPS35/29/26 recruitment and causes Rab7 to dissociate from the membrane. We therefore propose that recruitment of the cargo-selective VPS35/29/26 complex is catalysed by Rab7 and inhibited by the Rab-GAP protein, TBC1D5.
Seaman
Matthew N J
MN
University of Cambridge, Cambridge Institute for Medical Research, Department of Clinical Biochemistry, Wellcome Trust/MRC Building, Addenbrookes Hospital, Hills Road, Cambridge CB2 0XY, UK. mnjs100@cam.ac.uk
Harbour
Michael E
ME
Tattersall
Daniel
D
Read
Eliot
E
Bright
Nicholas
N
D022181:COP-Coated Vesicles / Q000378:metabolism*; D002607:Charcot-Marie-Tooth Disease / Q000235:genetics / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D011992:Endosomes / Q000378:metabolism*; D020690:GTPase-Activating Proteins / Q000235:genetics / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism*; D009154:Mutation; D021381:Protein Transport; D034622:RNA Interference; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014162:Transfection; D033921:Vesicular Transport Proteins / Q000235:genetics / Q000378:metabolism*; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D000090802:rab7 GTP-Binding Proteins
D020690:GTPase-Activating Proteins; D011993:Recombinant Fusion Proteins; C543487:TBC1D5 protein, human; C498296:VPS26A protein, human; C419572:VPS29 protein, human; C419573:VPS35 protein, human; D033921:Vesicular Transport Proteins; D000090802:rab7 GTP-Binding Proteins; C000716463:rab7 GTP-binding proteins, human; D020691:rab GTP-Binding Proteins