title: A conserved dileucine-containing motif in p6(gag) governs the particle association of Vpx and Vpr of simian immunodeficiency viruses SIV(mac) and SIV(agm).
abstract: Vpr is a small accessory protein of human and simian immunodeficiency viruses (HIV and SIV) that is specifically incorporated into virions. Members of the HIV-2/SIV(sm)/SIV(mac) lineage of primate lentiviruses also incorporate a related protein designated Vpx. We previously identified a highly conserved L-X-X-L-F sequence near the C terminus of the p6 domain of the Gag precursor as the major virion association motif for HIV-1 Vpr. In the present study, we show that a different leucine-containing motif (D-X-A-X-X-L-L) in the N-terminal half of p6(gag) is required for the incorporation of SIV(mac) Vpx. Similarly, the uptake of SIV(mac) Vpr depended primarily on the D-X-A-X-X-L-L motif. SIV(mac) Vpr was unstable when expressed alone, but its intracellular steady-state levels increased significantly in the presence of wild-type Gag or of the proteasome inhibitor lactacystin. Collectively, our results indicate that the interaction with the Gag precursor via the D-X-A-X-X-L-L motif diverts SIV(mac) Vpr away from the proteasome-degradative pathway. While absent from HIV-1 p6(gag), the D-X-A-X-X-L-L motif is conserved in both the HIV-2/SIV(sm)/SIV(mac) and SIV(agm) lineages of primate lentiviruses. We found that the incorporation of SIV(agm) Vpr, like that of SIV(mac) Vpx, is absolutely dependent on the D-X-A-X-X-L-L motif, while the L-X-X-L-F motif used by HIV-1 Vpr is dispensable. The similar requirements for the incorporation of SIV(mac) Vpx and SIV(agm) Vpr provide support for their proposed common ancestry.
authors.affiliation: Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Accola
authors.forename: A A
authors.initials: AA
authors.lastname: Bukovsky
authors.forename: M S
authors.initials: MS
authors.lastname: Jones
authors.forename: H G
authors.initials: HG
authors.lastname: Göttlinger
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017124:Conserved Sequence; D015683:Gene Products, gag / Q000235:genetics / Q000378:metabolism*; D016336:Gene Products, vpr / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007424:Intracellular Fluid; D007930:Leucine; D015302:Simian Immunodeficiency Virus / Q000502:physiology*; D054334:Viral Regulatory and Accessory Proteins / Q000235:genetics / Q000378:metabolism*; D014771:Virion; D019065:Virus Assembly; D054301:gag Gene Products, Human Immunodeficiency Virus
chemical_list: D015683:Gene Products, gag; D016336:Gene Products, vpr; C074286:VPX protein, Human immunodeficiency virus 2; C513059:VPX protein, Simian immunodeficiency virus; D054334:Viral Regulatory and Accessory Proteins; D054301:gag Gene Products, Human Immunodeficiency Virus; C083002:p6 gag protein, Human immunodeficiency virus 1; D007930:Leucine