title: Human immunodeficiency virus type 1 Vpr localization: nuclear transport of a viral protein modulated by a putative amphipathic helical structure and its relevance to biological activity.
abstract: Protein import into the nucleus is generally considered to involve specific nuclear localization signals (NLS) though it is becoming increasingly clear that efficient and well controlled import of proteins which lack a canonical NLS also occurs in cells. Human immunodeficiency virus type 1 (HIV-1) Vpr is one such protein which does not have an identifiable canonical NLS and yet efficiently localizes to the nuclear compartment. Here, we use confocal microscopy to demonstrate that mutations in the putative central hydrophobic helix of Vpr result in the retention of the protein in highly localized ring-like structures around the nuclear periphery with striking impairment in their ability to enter the nuclear interior. By characterizing other biological activities associated with this protein, such as its ability to incorporate into budding virions and its ability to arrest cells in G2, we show that this helical domain is specific for the nuclear translocation of the protein with very little effect on these other functions. Interestingly, however, perturbation of this helical motif also perturbs the protein's ability to augment viral replication in primary human macrophages indicating that the integrity of this secondary structure is essential for optimal infection in these non-dividing cells.
authors.affiliation: Department of Microbiology and Immunology, University of Montreal, Quebec, H3C 3J7, Canada.
authors.forename: R A
authors.initials: RA
authors.lastname: Subbramanian
authors.forename: X J
authors.initials: XJ
authors.lastname: Yao
authors.forename: H
authors.initials: H
authors.lastname: Dilhuydy
authors.forename: N
authors.initials: N
authors.lastname: Rougeau
authors.forename: D
authors.initials: D
authors.lastname: Bergeron
authors.forename: Y
authors.initials: Y
authors.lastname: Robitaille
authors.forename: E A
authors.initials: EA
authors.lastname: Cohen
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry; D000818:Animals; D017209:Apoptosis; D001692:Biological Transport; D019556:COS Cells; D002467:Cell Nucleus / Q000378:metabolism / Q000821:virology; D002478:Cells, Cultured; D053938:DNA Fragmentation; D016195:G2 Phase; D015870:Gene Expression; D016336:Gene Products, vpr / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015497:HIV-1 / Q000235:genetics / Q000502:physiology*; D006801:Humans; D008264:Macrophages / Q000821:virology; D008969:Molecular Sequence Data; D016296:Mutagenesis; D017433:Protein Structure, Secondary; D013329:Structure-Activity Relationship; D014771:Virion; D014779:Virus Replication; D054325:vpr Gene Products, Human Immunodeficiency Virus
chemical_list: D000596:Amino Acids; D016336:Gene Products, vpr; D054325:vpr Gene Products, Human Immunodeficiency Virus