title: Identification of a host protein essential for assembly of immature HIV-1 capsids.
abstract: To form an immature HIV-1 capsid, 1,500 HIV-1 Gag (p55) polypeptides must assemble properly along the host cell plasma membrane. Insect cells and many higher eukaryotic cell types support efficient capsid assembly, but yeast and murine cells do not, indicating that host machinery is required for immature HIV-1 capsid formation. Additionally, in a cell-free system that reconstitutes HIV-1 capsid formation, post-translational assembly events require ATP and a subcellular fraction, suggesting a requirement for a cellular ATP-binding protein. Here we identify such a protein (HP68), described previously as an RNase L inhibitor, and demonstrate that it associates post-translationally with HIV-1 Gag in a cell-free system and human T cells infected with HIV-1. Using a dominant negative mutant of HP68 in mammalian cells and depletion-reconstitution experiments in the cell-free system, we demonstrate that HP68 is essential for post-translational events in immature HIV-1 capsid assembly. Furthermore, in cells the HP68-Gag complex is associated with HIV-1 Vif, which is involved in virion morphogenesis and infectivity. These findings support a critical role for HP68 in post-translational events of HIV-1 assembly and reveal a previously unappreciated dimension of host-viral interaction.
authors.affiliation: Department of Physiology, University of California at San Francisco, San Francisco, California 94143, USA.
authors.forename: Concepcion
authors.initials: C
authors.lastname: Zimmerman
authors.forename: Kevin C
authors.initials: KC
authors.lastname: Klein
authors.forename: Patti K
authors.initials: PK
authors.lastname: Kiser
authors.forename: Aalok R
authors.initials: AR
authors.lastname: Singh
authors.forename: Bonnie L
authors.initials: BL
authors.lastname: Firestein
authors.forename: Shannyn C
authors.initials: SC
authors.lastname: Riba
authors.forename: Jaisri R
authors.initials: JR
authors.lastname: Lingappa
mesh_terms: D018528:ATP-Binding Cassette Transporters; D000818:Animals; D019556:COS Cells; D002213:Capsid / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002474:Cell-Free System; D018833:Chaperonins; D004722:Endoribonucleases / Q000378:metabolism; D015683:Gene Products, gag / Q000235:genetics / Q000378:metabolism; D015693:Gene Products, nef / Q000378:metabolism; D016346:Gene Products, vif / Q000378:metabolism; D015497:HIV-1 / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D006801:Humans; D007106:Immune Sera / Q000276:immunology; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011233:Precipitin Tests; D011485:Protein Binding; D014176:Protein Biosynthesis; D011498:Protein Precursors / Q000235:genetics / Q000378:metabolism; D011506:Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D020539:Sequence Analysis, Protein; D013379:Substrate Specificity; D013601:T-Lymphocytes / Q000378:metabolism / Q000821:virology; D014908:Triticum; D019065:Virus Assembly; D054311:nef Gene Products, Human Immunodeficiency Virus; D054320:vif Gene Products, Human Immunodeficiency Virus
chemical_list: C501917:ABCE1 protein, human; D018528:ATP-Binding Cassette Transporters; D015683:Gene Products, gag; D015693:Gene Products, nef; D016346:Gene Products, vif; D007106:Immune Sera; D011498:Protein Precursors; D011506:Proteins; D054311:nef Gene Products, Human Immunodeficiency Virus; C059767:p55 gag precursor protein, Human immunodeficiency virus 1; D054320:vif Gene Products, Human Immunodeficiency Virus; D004722:Endoribonucleases; C031956:2-5A-dependent ribonuclease; D018833:Chaperonins