title: Characterization of RNA binding and chaperoning activities of HIV-1 Vif protein. Importance of the C-terminal unstructured tail.
abstract: The viral infectivity factor (Vif) is essential for the productive infection and dissemination of HIV-1 in non-permissive cells, containing the cellular anti-HIV defense cytosine deaminases APOBEC3 (A3G and A3F). Vif neutralizes the antiviral activities of the APOBEC3G/F by diverse mechanisms including their degradation through the ubiquitin/proteasome pathway and their translational inhibition. In addition, Vif appears to be an active partner of the late steps of viral replication by interacting with Pr55(Gag), reverse transcriptase and genomic RNA. Here, we expressed and purified full-length and truncated Vif proteins, and analyzed their RNA binding and chaperone properties. First, we showed by CD and NMR spectroscopies that the N-terminal domain of Vif is highly structured in solution, whereas the C-terminal domain remains mainly unfolded. Both domains exhibited substantial RNA binding capacities with dissociation constants in the nanomolar range, whereas the basic unfolded C-terminal domain of Vif was responsible in part for its RNA chaperone activity. Second, we showed by NMR chemical shift mapping that Vif and NCp7 share the same binding sites on tRNA(Lys) 3, the primer of HIV-1 reverse transcriptase. Finally, our results indicate that Vif has potent RNA chaperone activity and provide direct evidence for an important role of the unstructured C-terminal domain of Vif in this capacity.
authors.forename: Dona
authors.initials: D
authors.lastname: Sleiman
authors.forename: Serena
authors.initials: S
authors.lastname: Bernacchi
authors.forename: Santiago
authors.initials: S
authors.lastname: Xavier Guerrero
authors.forename: Franck
authors.initials: F
authors.lastname: Brachet
authors.forename: Valéry
authors.initials: V
authors.lastname: Larue
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Paillart
authors.forename: Carine
authors.initials: C
authors.lastname: Tisne
mesh_terms: D001665:Binding Sites; D002942:Circular Dichroism; D015497:HIV-1 / Q000378:metabolism*; D018832:Molecular Chaperones / Q000378:metabolism*; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding; D017433:Protein Structure, Secondary; D012343:RNA, Transfer / Q000378:metabolism*; D054301:gag Gene Products, Human Immunodeficiency Virus / Q000737:chemistry / Q000378:metabolism; D054320:vif Gene Products, Human Immunodeficiency Virus / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D018832:Molecular Chaperones; C071884:NCP7 protein, Human immunodeficiency virus 1; D054301:gag Gene Products, Human Immunodeficiency Virus; D054320:vif Gene Products, Human Immunodeficiency Virus; C514847:vif protein, Human immunodeficiency virus 1; D012343:RNA, Transfer
keywords: HIV; RNA chaperone; Vif; nucleocapsid; unstructured domain