title: APOBEC3G impairs the multimerization of the HIV-1 Vif protein in living cells.
abstract: The HIV-1 viral infectivity factor (Vif) is a small basic protein essential for viral fitness and pathogenicity. Vif allows productive infection in nonpermissive cells, including most natural HIV-1 target cells, by counteracting the cellular cytosine deaminases APOBEC3G (apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like 3G [A3G]) and A3F. Vif is also associated with the viral assembly complex and packaged into viral particles through interactions with the viral genomic RNA and the nucleocapsid domain of Pr55(Gag). Recently, we showed that oligomerization of Vif into high-molecular-mass complexes induces Vif folding and influences its binding to high-affinity RNA binding sites present in the HIV genomic RNA. To get further insight into the role of Vif multimerization in viral assembly and A3G repression, we used fluorescence lifetime imaging microscopy (FLIM)- and fluorescence resonance energy transfer (FRET)-based assays to investigate Vif-Vif interactions in living cells. By using two N-terminally tagged Vif proteins, we show that Vif-Vif interactions occur in living cells. This oligomerization is strongly reduced when the putative Vif multimerization domain ((161)PPLP(164)) is mutated, indicating that this domain is crucial, but that regions outside this motif also participate in Vif oligomerization. When coexpressed together with Pr55(Gag), Vif is largely relocated to the cell membrane, where Vif oligomerization also occurs. Interestingly, wild-type A3G strongly interferes with Vif multimerization, contrary to an A3G mutant that does not bind to Vif. These findings confirm that Vif oligomerization occurs in living cells partly through its C-terminal motif and suggest that A3G may target and perturb the Vif oligomerization state to limit its functions in the cell.
authors.affiliation: Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, Institut de Biologie Moléculaire et Cellulaire, Strasbourg Cedex, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Batisse
authors.forename: Santiago Xavier
authors.initials: SX
authors.lastname: Guerrero
authors.forename: Serena
authors.initials: S
authors.lastname: Bernacchi
authors.forename: Ludovic
authors.initials: L
authors.lastname: Richert
authors.forename: Julien
authors.initials: J
authors.lastname: Godet
authors.forename: Valérie
authors.initials: V
authors.lastname: Goldschmidt
authors.forename: Yves
authors.initials: Y
authors.lastname: Mély
authors.forename: Roland
authors.initials: R
authors.lastname: Marquet
authors.forename: Hugues
authors.initials: H
authors.lastname: de Rocquigny
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Paillart
mesh_terms: D000071480:APOBEC-3G Deaminase; D020816:Amino Acid Motifs; D003564:Cytidine Deaminase / Q000235:genetics / Q000378:metabolism*; D015658:HIV Infections / Q000201:enzymology* / Q000235:genetics / Q000821:virology; D015497:HIV-1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D055503:Protein Multimerization; D054320:vif Gene Products, Human Immunodeficiency Virus / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D054320:vif Gene Products, Human Immunodeficiency Virus; D000071480:APOBEC-3G Deaminase; C464924:APOBEC3G protein, human; D003564:Cytidine Deaminase