title: A novel tribasic Golgi export signal directs cargo protein interaction with activated Rab11 and AP-1-dependent Golgi-plasma membrane trafficking.
abstract: The reovirus fusion-associated small transmembrane (FAST) proteins comprise a unique family of viral membrane fusion proteins dedicated to inducing cell-cell fusion. We recently reported that a polybasic motif (PBM) in the cytosolic tail of reptilian reovirus p14 FAST protein functions as a novel tribasic Golgi export signal. Using coimmunoprecipitation and fluorescence resonance energy transfer (FRET) assays, we now show the PBM directs interaction of p14 with GTP-Rab11. Overexpression of dominant-negative Rab11 and RNA interference knockdown of endogenous Rab11 inhibited p14 plasma membrane trafficking and resulted in p14 accumulation in the Golgi complex. This is the first example of Golgi export to the plasma membrane that is dependent on the interaction of membrane protein cargo with activated Rab11. RNA interference and immunofluorescence microscopy further revealed that p14 Golgi export is dependent on AP-1 (but not AP-3 or AP-4) and that Rab11 and AP-1 both colocalize with p14 at the TGN. Together these results imply the PBM mediates interactions of p14 with activated Rab11 at the TGN, resulting in p14 sorting into AP1-coated vesicles for anterograde TGN-plasma membrane transport.
authors.affiliation: Department of Microbiology and Immunology, Dalhousie University, Halifax, NS B3H 4R2, Canada.
authors.forename: Hirendrasinh B
authors.initials: HB
authors.lastname: Parmar
authors.affiliation: Department of Microbiology and Immunology, Dalhousie University, Halifax, NS B3H 4R2, Canada Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada Department of Pediatrics, Dalhousie University, Halifax, NS B3H 4R2, Canada roy.duncan@dal.ca.
authors.forename: Roy
authors.initials: R
authors.lastname: Duncan
mesh_terms: D002462:Cell Membrane / Q000378:metabolism; D018699:Coated Vesicles / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D054730:Protein Interaction Domains and Motifs; D021382:Protein Sorting Signals; D021381:Protein Transport; D018808:Transcription Factor AP-1 / Q000235:genetics / Q000378:metabolism*; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D000099193:rab11 GTP-Binding Proteins
chemical_list: D006160:Guanosine Triphosphate; D021382:Protein Sorting Signals; D018808:Transcription Factor AP-1; D014764:Viral Proteins; D020691:rab GTP-Binding Proteins; D000099193:rab11 GTP-Binding Proteins