title: The interaction between HIV-1 Gag and APOBEC3G.
abstract: APOBEC3G, a member of an RNA/DNA cytidine deaminase superfamily, has been identified as a cellular inhibitor of HIV-1 infectivity, possibly through the dC to dU deamination of the first minus strand cDNA synthesized during reverse transcription. Virions incorporate APOBEC3G during viral assembly in non-permissive cells, and this incorporation is inhibited by the viral protein Vif. The mechanism of APOBEC3G incorporation into HIV-1 is examined in this report. In the absence of Vif, cytoplasmic APOBEC3G becomes membrane-bound in cells expressing HIV-1 Gag, and its incorporation into Gag viral-like particles (VLPs) is proportional to the amount of APOBEC3G expressed in the cell. The expression of Vif, or mutant Gag unable to bind to membrane, prevents the APOBEC3G association with membrane. HIV-1 Gag alone among viral proteins is sufficient for packaging of APOBEC3G into Gag VLPs, and this incorporation requires the presence of Gag nucleocapsid. The presence of amino acids 104-156 in APOBEC3G, located in the linker region between two zinc coordination motifs, is also required for its incorporation into Gag VLPs. Evidence against an RNA bridge facilitating the Gag/APOBEC3G interaction includes data indicating that 1) the incorporation of APOBEC3G occurs independently of viral genomic RNA, 2) a Gag/APOBEC3G complex is immunoprecipitated from cell lysate after RNase treatment, and 3) the zinc coordination motif, rather than the regions flanking this motif, have been implicated in RNA binding in another family member, APOBEC1.
authors.affiliation: Lady Davis Institute for Medical Research and McGill AIDS Centre, Jewish General Hospital, Department of Medicine, McGill University, Montreal, Quebec H3T 1E2, Canada.
authors.forename: Shan
authors.initials: S
authors.lastname: Cen
authors.forename: Fei
authors.initials: F
authors.lastname: Guo
authors.forename: Meijuan
authors.initials: M
authors.lastname: Niu
authors.forename: Jenan
authors.initials: J
authors.lastname: Saadatmand
authors.forename: Julien
authors.initials: J
authors.lastname: Deflassieux
authors.forename: Lawrence
authors.initials: L
authors.lastname: Kleiman
mesh_terms: D000071480:APOBEC-3G Deaminase; D000595:Amino Acid Sequence; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D003564:Cytidine Deaminase; D003593:Cytoplasm / Q000378:metabolism; D004347:Drug Interactions; D015870:Gene Expression; D015683:Gene Products, gag / Q000235:genetics / Q000502:physiology*; D016346:Gene Products, vif / Q000502:physiology; D015497:HIV-1 / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D007163:Immunosorbent Techniques; D016297:Mutagenesis, Site-Directed; D009700:Nucleoside Deaminases; D011506:Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012367:RNA, Viral / Q000378:metabolism; D012097:Repressor Proteins; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012260:Ribonucleases / Q000494:pharmacology; D013329:Structure-Activity Relationship; D014162:Transfection; D014771:Virion / Q000378:metabolism; D016335:Zinc Fingers; D054320:vif Gene Products, Human Immunodeficiency Virus
chemical_list: D015683:Gene Products, gag; D016346:Gene Products, vif; D011506:Proteins; D012367:RNA, Viral; D012097:Repressor Proteins; D054320:vif Gene Products, Human Immunodeficiency Virus; D012260:Ribonucleases; D009700:Nucleoside Deaminases; D000071480:APOBEC-3G Deaminase; C464924:APOBEC3G protein, human; D003564:Cytidine Deaminase