HIV-1 encodes the accessory protein Vif, which hijacks a host Cullin-RING ubiquitin ligase (CRL) complex as well as the non-canonical cofactor CBFβ, to antagonize APOBEC3 antiviral proteins. Non-canonical cofactor recruitment to CRL complexes by viral factors, to date, has only been attributed to HIV-1 Vif. To further study this phenomenon, we employed a comparative approach combining proteomic, biochemical, structural, and virological techniques to investigate Vif complexes across the lentivirus genus, including primate (HIV-1 and simian immunodeficiency virus macaque [SIVmac]) and non-primate (FIV, BIV, and MVV) viruses. We find that CBFβ is completely dispensable for the activity of non-primate lentiviral Vif proteins. Furthermore, we find that BIV Vif requires no cofactor and that MVV Vif requires a novel cofactor, cyclophilin A (CYPA), for stable CRL complex formation and anti-APOBEC3 activity. We propose modular conservation of Vif complexes allows for potential exaptation of functions through the acquisition of non-CRL-associated host cofactors while preserving anti-APOBEC3 activity.
Bibliographical noteFunding Information:
The authors wish to thank members of the N.J.K., J.D.G., J.S.F., R.S.H., and V.A. labs; P. Hartley for assisting in stable line generation; R. LaRue for cloning of MVV, BIV, FIV, and SIVmac Vif plasmids; S. Jäger, S. Chen, M. Eckhardt, and D. Gordon for reagents; Z. Rizvi for CYPA cloning; S.J., C. Mahon, and G. Jang for expertise and advice in affinity purifications; E. Verschueren and P. Cimermančič for advice on AP-MS scoring; and M. Shales for assistance in figure construction. We would kindly thank S.J. Kim for help in collecting SAXS profiles and D. Schneidman for her assistance in generating the HIV E3 model and analyzing the SAXS data using the AllosMod-FoXS server. The following reagents were obtained through the NIH AIDS Reagent Program, Division of AIDS, NIAID, NIH: Jurkat Clone E6-1 from Dr. A. Weiss and Jurkat T cells CYPA −/− from Drs. D. Braaten and J. Luban. J.R.K. was supported by an NSF graduate research fellowship. This work was supported by NIH grants to N.J.K (P50 GM082250, P50 GM081879, and P01 AI090935) and to R.S.H. (R01 AI064046 and P01 GM091743) and a grant from the Icelandic Research Fund to V.A. (141085-051).
© 2015 The Authors.