title: The N-terminal matrix domain of HIV-1 Gag is sufficient but not necessary for viral protein U-mediated enhancement of particle release through a membrane-targeting mechanism.
abstract: Viral protein U (Vpu) is an 81 amino acid phosphoprotein found in human immunodeficiency virus type 1 (HIV-1)-infected cells. One function of Vpu is to enhance the release of virus particles from the plasma membrane in infected cells. Using subcellular fractionation, we observed that Vpu promotes the targeting of Pr55 Gag to the plasma membrane, the site of viral assembly. Deletions of Pr55, which removed most of the N-terminal matrix domain (p39) or the C-terminal domains of nucleocapsid and p6 (p41), still allowed for virus-like particle production. Moreover, the release of these particles remained Vpu-responsive. The N-terminal matrix (MA) domain of Gag, which contains its membrane-binding domain, is sufficient for Vpu-mediated enhanced release into the supernatant. Furthermore, a MA-GFP fusion protein showed enhanced membrane binding in the presence of Vpu. This demonstrates that Vpu action may be mediated by allowing Gag, specifically the N-terminal matrix domain, to efficiently associate with the plasma membrane. Thus MA appears sufficient but not necessary for Vpu-mediated enhanced particle release.
authors.affiliation: Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, 63110, USA.
authors.forename: A
authors.initials: A
authors.lastname: Deora
authors.forename: P
authors.initials: P
authors.lastname: Spearman
authors.forename: L
authors.initials: L
authors.lastname: Ratner
mesh_terms: D002462:Cell Membrane / Q000378:metabolism; D015683:Gene Products, gag / Q000502:physiology*; D015497:HIV-1; D006367:HeLa Cells; D054298:Human Immunodeficiency Virus Proteins; D006801:Humans; D018613:Microscopy, Confocal; D011498:Protein Precursors / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D054334:Viral Regulatory and Accessory Proteins / Q000502:physiology*; D000086082:Viroporin Proteins
chemical_list: D015683:Gene Products, gag; D054298:Human Immunodeficiency Virus Proteins; D011498:Protein Precursors; D011993:Recombinant Fusion Proteins; D054334:Viral Regulatory and Accessory Proteins; C059767:p55 gag precursor protein, Human immunodeficiency virus 1; C514859:vpu protein, Human immunodeficiency virus 1; D000086082:Viroporin Proteins