title: Characterization of a novel Cullin5 binding domain in HIV-1 Vif.
abstract: Human immunodeficiency virus tyoe 1 (HIV-1) Vif counteracts host restriction cytidine deaminase (APOBEC3G) A3G by co-opting the cellular ubiquitin-proteasome machinery. Vif utilizes a viral-specific BC-box to recruit ElonginB-ElonginC and a novel zinc-binding HCCH motif to recruit Cullin5 (Cul5) to form an E3 ubiquitin ligase targeting A3G for polyubiquitination and subsequently proteasomal degradation. To determine the structural requirements in HIV-1 Vif HCCH motif for Cul5 binding and Vif function, we investigated the arrangement of the His and Cys residues, the role of the spacing between them, and the requirement for the conserved residues. Our data demonstrate that exchanging Cys for His and vice versa in the highly conserved Zn-coordinating HCCH motif disrupted Vif function and interaction with Cul5. Moreover, the maintenance of both conserved residues and spacing within the HCCH motif is critical for Vif function. We have identified a "viral Cul5 box" with consensus Hx2YFxCFx4Phix2APhix7-8Cx5H that is required for Cul5 selection and subsequent A3G degradation. This novel motif may represent a potential new target for anti-viral drug development.
authors.affiliation: Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA.
authors.forename: Zuoxiang
authors.initials: Z
authors.lastname: Xiao
authors.forename: Yong
authors.initials: Y
authors.lastname: Xiong
authors.forename: Wenyan
authors.initials: W
authors.lastname: Zhang
authors.forename: Lindi
authors.initials: L
authors.lastname: Tan
authors.forename: Elana
authors.initials: E
authors.lastname: Ehrlich
authors.forename: Deyin
authors.initials: D
authors.lastname: Guo
authors.forename: Xiao-Fang
authors.initials: XF
authors.lastname: Yu
mesh_terms: D044842:Cullin Proteins / Q000378:metabolism*; D015497:HIV-1 / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D008954:Models, Biological; D011485:Protein Binding; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism; D054875:Ubiquitination; D015032:Zinc / Q000378:metabolism; D054320:vif Gene Products, Human Immunodeficiency Virus / Q000737:chemistry / Q000378:metabolism*
chemical_list: C496871:CUL5 protein, human; D044842:Cullin Proteins; D054320:vif Gene Products, Human Immunodeficiency Virus; D044767:Ubiquitin-Protein Ligases; D015032:Zinc