title: Separable determinants of subcellular localization and interaction account for the inability of group O HIV-1 Vpu to counteract tetherin.
abstract: Tetherin (BST-2/CD317) is thought to restrict retroviral particle release by cross-linking nascent viral and cellular membranes. Unlike the Vpu proteins encoded by human immunodeficiency virus type 1 (HIV-1) group M strains (M-Vpu), those from the nonpandemic HIV-1 group O (O-Vpu) are not able to counteract tetherin activity. Here, we characterized the basis of this defect in O-Vpu. O-Vpu differs from M-Vpu in that it fails to interact with tetherin and downregulate it from the cell surface. Unlike M-Vpu, O-Vpu localizes to the endoplasmic reticulum (ER) rather than the trans-Golgi network (TGN). Interestingly M-Vpu bearing an ER retention signal at the C terminus localizes similarly to O-Vpu. While it still interacts with tetherin, it fails to promote virus release, suggesting that O-Vpu deficiency correlates with its cellular distribution in the endoplasmic reticulum as well as its failure to bind tetherin. O-Vpu-M-Vpu chimeras were designed to identify the minimal changes required to restore tetherin antagonism. While several chimeric proteins bearing residues of the M-Vpu transmembrane domain into the O-Vpu transmembrane domain recovered tetherin binding in coimmunoprecipitation studies, efficient antagonism required an additional glutamic acid-to-lysine change in the membrane-proximal hinge region of the O-Vpu cytoplasmic tail that was sufficient to abolish ER retention and permit TGN localization.
authors.affiliation: Department of Infectious Disease, King's College London School of Medicine, Guy's Hospital, London SE1 9RT, UK.
authors.forename: Raphaël
authors.initials: R
authors.lastname: Vigan
authors.forename: Stuart J D
authors.initials: SJ
authors.lastname: Neil
mesh_terms: D015703:Antigens, CD; D004721:Endoplasmic Reticulum / Q000737:chemistry; D058851:GPI-Linked Proteins / Q000037:antagonists & inhibitors; D015497:HIV-1 / Q000472:pathogenicity*; D006367:HeLa Cells; D054298:Human Immunodeficiency Virus Proteins / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D011485:Protein Binding; D025941:Protein Interaction Mapping; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D054334:Viral Regulatory and Accessory Proteins / Q000235:genetics* / Q000378:metabolism*; D037521:Virulence Factors / Q000235:genetics* / Q000378:metabolism*; D057074:Virus Release; D021601:trans-Golgi Network / Q000737:chemistry; D000074010:Bone Marrow Stromal Antigen 2; D000086082:Viroporin Proteins
chemical_list: D015703:Antigens, CD; D058851:GPI-Linked Proteins; D054298:Human Immunodeficiency Virus Proteins; D011994:Recombinant Proteins; D054334:Viral Regulatory and Accessory Proteins; D037521:Virulence Factors; C094572:BST2 protein, human; D000074010:Bone Marrow Stromal Antigen 2; C514859:vpu protein, Human immunodeficiency virus 1; D000086082:Viroporin Proteins