HIV type 1 viral infectivity factor and the RUNX transcription factors interact with core binding factor β on genetically distinct surfaces.
Human immunodeficiency virus type 1 (HIV-1) requires the cellular transcription factor core binding factor subunit β (CBFβ) to stabilize its viral infectivity factor (Vif) protein and neutralize the APOBEC3 restriction factors. CBFβ normally heterodimerizes with the RUNX family of transcription factors, enhancing their stability and DNA-binding affinity. To test the hypothesis that Vif may act as a RUNX mimic to bind CBFβ, we generated a series of CBFβ mutants at the RUNX/CBFβ interface and tested their ability to stabilize Vif and impact transcription at a RUNX-dependent promoter. While several CBFβ amino acid substitutions disrupted promoter activity, none of these impacted the ability of CBFβ to stabilize Vif or enhance degradation of APOBEC3G. A mutagenesis screen of CBFβ surface residues identified a single amino acid change, F68D, that disrupted Vif binding and its ability to degrade APOBEC3G. This mutant still bound RUNX and stimulated RUNX-dependent transcription. These separation-of-function mutants demonstrate that HIV-1 Vif and the RUNX transcription factors interact with cellular CBFβ on genetically distinct surfaces.
Department of Biochemistry, Molecular Biology and Biophysics, Institute for Molecular Virology, Center for Genome Engineering, Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA.
Judd F
JF
Hultquist
Rebecca M
RM
McDougle
Brett D
BD
Anderson
Reuben S
RS
Harris
D000071480:APOBEC-3G Deaminase; D019943:Amino Acid Substitution; D050657:Core Binding Factor alpha Subunits / Q000378:metabolism*; D050658:Core Binding Factor beta Subunit / Q000235:genetics / Q000378:metabolism*; D003564:Cytidine Deaminase / Q000378:metabolism*; D015497:HIV-1 / Q000472:pathogenicity*; D054884:Host-Pathogen Interactions; D006801:Humans; D016297:Mutagenesis, Site-Directed; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D025941:Protein Interaction Mapping; D059748:Proteolysis; D054320:vif Gene Products, Human Immunodeficiency Virus / Q000378:metabolism*
D050657:Core Binding Factor alpha Subunits; D050658:Core Binding Factor beta Subunit; D050505:Mutant Proteins; D054320:vif Gene Products, Human Immunodeficiency Virus; C514847:vif protein, Human immunodeficiency virus 1; D000071480:APOBEC-3G Deaminase; C464924:APOBEC3G protein, human; D003564:Cytidine Deaminase