Nucleic Acids Research Advance Access published online on April 15, 2009
Nucleic Acids Research, doi:10.1093/nar/gkp226
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Molecular Biology |
Mutational analysis of the HIV-1 auxiliary protein Vif identifies independent domains important for the physical and functional interaction with HIV-1 reverse transcriptase
1Institute of Molecular Genetics IGM-CNR, via Abbiategrasso 207, I-27100 Pavia and 2AIDS Therapy, MolMed S.p.A.,via Olgettina 58, I-20132 Milano, Italy
*To whom correspondence should be addressed. Tel: +39 0382 546354; Fax: +39 0382 422286; Email: maga{at}igm.cnr.it
Received December 22, 2008. Revised March 23, 2009. Accepted March 24, 2009.
The HIV-1 accessory protein Vif plays a dual role: it counteracts the natural restriction factors APOBEC3G and 3F and ensures efficient retrotranscription of the HIV-1 RNA genome. We have previously shown that Vif can act as an auxiliary factor for HIV-1 reverse transcriptase (RT), increasing its rate of association to RNA or DNA templates. Here, by using seven different Vif mutants, we provide in vitro evidences that Vif stimulates HIV-1 RT through direct protein–protein interaction, which is mediated by its C-terminal domain. Physical interaction appears to require the proline-rich region comprised between amino acid (aa) 161 and 164 of Vif, whereas the RT stimulatory activity requires, in addition, the extreme C-terminal region (aa 169–192) of the Vif protein. Neither the RNA interaction domain, nor the Zn++-binding domain of Vif are required for its interaction with the viral RT. Pseudotyped HIV-1 lentiviral vectors bearing Vif mutants deleted in the RNA- or RT-binding domains show defects in retrotranscription/integration processes in both permissive and nonpermissive cells. Our results broaden our knowledge on how three important functions of Vif (RNA binding, RT binding and stimulation and Zn++ binding), are coordinated by different domains.