University of Saskatchewan, Biochemistry, Microbiology, and Immunology, College of Medicine, Saskatoon, Saskatchewan, Canada; Saskatchewan HIV/AIDS Research Endeavour, Saskatoon, Saskatchewan, Canada. Electronic address: [Email]
The APOBEC3 enzyme family are host restriction factors that induce mutagenesis of HIV-1 proviral genomes through the deamination of cytosine to form uracil in nascent single-stranded (-)DNA. HIV-1 suppresses APOBEC3 activity through the HIV-1 protein Vif that induces APOBEC3 degradation. Here we compared two common polymorphisms of APOBEC3F. We found that although both polymorphisms have HIV-1 restriction activity, APOBEC3F 108 A/231V can restrict HIV-1 ΔVif up to 4-fold more than APOBEC3F 108 S/231I and is partially protected from Vif-mediated degradation. This resulted from higher levels of steady state expression of APOBEC3F 108 A/231 V. Individuals are commonly heterozygous for the APOBEC3F polymorphisms and these polymorphisms formed in cells, independent of RNA, hetero-oligomers between each other and with APOBEC3G. Hetero-oligomerization with APOBEC3F 108 A/231V resulted in partial stabilization of APOBEC3F 108 S/231I and APOBEC3G in the presence of Vif. These data demonstrate functional outcomes of APOBEC3 polymorphisms and hetero-oligomerization that affect HIV-1 restriction.