A zinc-binding region in Vif binds Cul5 and determines cullin selection.
Human immunodeficiency virus-1 (HIV-1) Vif overcomes the anti-viral activity of APOBEC3G by targeting it for ubiquitination via a Cullin 5-ElonginB-ElonginC (Cul5-EloBC) E3 ligase. Vif associates with Cul5-EloBC through a BC-box motif that binds EloC, but the mechanism by which Vif selectively recruits Cul5 is poorly understood. Here we report that a region of Vif (residues 100-142) upstream of the BC-box binds selectively to Cul5 in the absence of EloC. This region contains a zinc coordination site HX5CX17-18CX3-5H (HCCH), with His/Cys residues at positions 108, 114, 133, and 139 coordinating one zinc ion. The HCCH zinc coordination site, which is conserved among primate lentivirus Vif proteins, does not correspond to any known class of zinc-binding motif. Mutations of His/Cys residues in the HCCH motif impair zinc coordination, Cul5 binding, and APOBEC3G degradation. Mutations of conserved hydrophobic residues (Ile-120, Ala-123, and Leu-124) located between the two Cys residues in the HCCH motif disrupt binding of the zinc-coordinating region to Cul5 and inhibit APOBEC3G degradation. The Vif binding site maps to the first cullin repeat in the N terminus of Cul5. These data suggest that the zinc-binding region in Vif is a novel cullin interaction domain that mediates selective binding to Cul5. We propose that the HCCH zinc-binding motif facilitates Vif-Cul5 binding by playing a structural role in positioning hydrophobic residues for direct contact with Cul5.
Mehle
Andrew
A
Department of Cancer Immunology and AIDS, Dana Farber Cancer Institute, Boston, Massachusetts 02115; Departments of Pathology, Harvard Medical School, Boston, Massachusetts 02115.
Thomas
Elaine R
ER
Department of Cancer Immunology and AIDS, Dana Farber Cancer Institute, Boston, Massachusetts 02115; Departments of Pathology, Harvard Medical School, Boston, Massachusetts 02115.
Rajendran
Kottampatty S
KS
Department of Cancer Immunology and AIDS, Dana Farber Cancer Institute, Boston, Massachusetts 02115; Departments of Pathology, Harvard Medical School, Boston, Massachusetts 02115.
Gabuzda
Dana
D
Department of Cancer Immunology and AIDS, Dana Farber Cancer Institute, Boston, Massachusetts 02115; Departments of Neurology, Harvard Medical School, Boston, Massachusetts 02115. Electronic address: dana_gabuzda@dfci.harvard.edu.
D000071478:APOBEC Deaminases; D000595:Amino Acid Sequence; D045744:Cell Line, Tumor; D044842:Cullin Proteins / Q000737:chemistry*; D003564:Cytidine Deaminase; D043525:Cytosine Deaminase / Q000737:chemistry; D016346:Gene Products, vif / Q000737:chemistry*; D015497:HIV-1 / Q000378:metabolism; D006801:Humans; D008954:Models, Biological; D008969:Molecular Sequence Data; D011485:Protein Binding; D017386:Sequence Homology, Amino Acid; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry; D015032:Zinc / Q000737:chemistry*; D054320:vif Gene Products, Human Immunodeficiency Virus
C496871:CUL5 protein, human; D044842:Cullin Proteins; D016346:Gene Products, vif; D054320:vif Gene Products, Human Immunodeficiency Virus; D044767:Ubiquitin-Protein Ligases; D043525:Cytosine Deaminase; D000071478:APOBEC Deaminases; C502889:APOBEC3 proteins, human; D003564:Cytidine Deaminase; D015032:Zinc