The HIV-1 Vif PPLP motif is necessary for human APOBEC3G binding and degradation

Abstract

The HIV-1 virion infectivity factor (Vif) is required during viral replication to inactivate the host cell anti-viral factor, APOBEC3G (A3G). Vif binds A3G and a Cullin5-ElonginBC E3 ubiquitin ligase complex which results in the proteasomal degradation of A3G. The Vif PPLP motif (amino acids 161-164) is essential for normal Vif function because mutations in this motif reduce the infectivity of virions produced in T-cells. In this report, we demonstrate that mutation of the Vif PPLP motif reduces Vif binding to A3G without affecting its interaction with ElonginC and Cullin5. We demonstrate that the failure of the Vif mutant to bind A3G resulted in A3G incorporation into assembling virions with loss of viral infectivity.

APOBEC3G Impairs the Multimerization of the HIV-1 Vif Protein in Living Cells

“…Thus, these two proteins were also efficiently expressed in HeLa cells. As previously observed (40,57), these Vif AALA mutants were inefficient in counteracting A3G ( Fig. 2A, lanes 4, 6, and 8, and B), confirming the importance of the PPLP motif in the A3G regulation.…”

“…The A3G protein is a potent innate antiviral factor, and Vif has been shown to restrict its activity by inducing its degradation through the proteasome, inhibiting its translation and its incorporation into viral particles (for reviews, see references 1 and 5). Most of these activities involve physical interactions between Vif and A3G, and interacting motifs have been previously defined, mostly in the N terminus of each protein (66), but discrete motifs in the C terminus of Vif, such as the PPLP motif, have also been shown to bind A3G (40,57). To investigate whether the binding of A3G to Vif affects its oligomerization, we transfected HeLa cells with the eGFP-and mCherry-Vif constructs together with an A3G expression vector and analyzed the eGFP-Vif lifetime 24 h posttransfection (Fig.…”

“…This short domain was found to be crucial for Vif function and viral infectivity (37)(38)(39). Moreover, it can interact with A3G (40,41), cullin 5 (42), and the HIV-1 reverse transcriptase (35), and it was also observed that an intact PPLP motif is required for interaction between Vif and elongin B (43,44). Considering the involvement of the PPLP motif in Vif oligomerization, it is conceivable that all of these binding functions could be linked to the multimerization state of Vif.…”

L’adaptation des lentivirus au chimpanzé

“…Bien que le rôle précis de ce motif soit mal connu, sa mutation affecte la capacité du VIH-1 Vif à dégrader l'A3G [7,8]. Ce nouveau domaine carboxy-terminal de Vif, qui a été généré lors de la création du SIVcpz et parallèlement à la perte du vpx, a été conservé dans les virus descendants, SIVgor et VIH-1, et joue donc un rôle dans l'inhibition du facteur de restriction A3G [6].…”

Tumultuous Relationship between the Human Immunodeficiency Virus Type 1 Viral Infectivity Factor (Vif) and the Human APOBEC-3G and APOBEC-3F Restriction Factors

“…In addition, mutations in the 161PPLP164 motif, which is located in the C-terminal region of Vif ( Fig. 1), reduce Vif binding to hA3G and the degradation of this restriction factor without affecting the interaction of Vif with Elongin C and Cullin5 (54). Interestingly, the level of incorporation of hA3G into WT HIV-1 particles can be increased by a peptide mimicking the Vif PPLP dimerization domain, and this peptide displays anti-HIV-1 activity (158).…”