title: Feline immunodeficiency virus Orf-A localizes to the nucleus and induces cell cycle arrest.
abstract: Feline immunodeficiency virus (FIV) gene orf-A, also designated orf-2, encodes a 77 amino acid accessory protein reported to be critical for efficient viral replication in vitro and in vivo and previously implicated to encode a Tat protein for FIV. However, recent studies have shown Orf-A to be important in the late steps of the FIV life cycle involved in virion formation and in early steps involved in virus infectivity. The present study reports that expression of a GFP-Orf-A fusion protein in both primate and feline cell lines results in nuclear localization of this FIV accessory protein. Moreover, a nuclear localization signal (NLS) critical for nuclear import was mapped to amino acid residues 43 through 53 of Orf-A. Lastly, transient expression of GFP-Orf-A in cells induced an arrest at the second gap (G(2)) of the cell cycle. Our findings reveal that Orf-A is a nuclear protein that expresses properties similar to those reported for human immunodeficiency virus-1 (HIV-1)-encoded Vpr.
authors.affiliation: Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
authors.forename: Malou C
authors.initials: MC
authors.lastname: Gemeniano
authors.forename: Earl T
authors.initials: ET
authors.lastname: Sawai
authors.forename: Ellen E
authors.initials: EE
authors.lastname: Sparger
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D002453:Cell Cycle; D002467:Cell Nucleus / Q000821:virology; D005814:Genes, Viral; D016089:Immunodeficiency Virus, Feline / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*; D008969:Molecular Sequence Data; D009154:Mutation; D019913:Nuclear Localization Signals / Q000235:genetics; D016366:Open Reading Frames; D010449:Peptide Mapping; D010957:Plasmids / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014764:Viral Proteins / Q000235:genetics / Q000502:physiology*
chemical_list: D019913:Nuclear Localization Signals; D011993:Recombinant Fusion Proteins; D014764:Viral Proteins