title: The enzymatic activity of CEM15/Apobec-3G is essential for the regulation of the infectivity of HIV-1 virion but not a sole determinant of its antiviral activity.
abstract: Human immunodeficiency virus, type 1 (HIV-1) Vif protein plays an essential role in the regulation of the infectivity of HIV-1 virion. Vif functions to counteract an anti-HIV-1 cellular factor in non-permissive cells, CEM15/Apobec-3G, which shares a cytidine deaminase motif. CEM15/Apobec-3G deaminates dC to dU in the minus strand DNA of HIV-1, resulting in G to A hypermutation in the plus strand DNA. In this study, we have done the mutagenesis analysis on two cytidine deaminase motifs in CEM15/Apobec-3G and examined their antiviral functions as well as the DNA editing activity. Point mutations in the C-terminal active site such as E259Q and C291A almost completely abrogated the antiviral function, while those in the N-terminal active site such as E67Q and C100A retained this activity to a lesser extent as compared with that of the wild type. The DNA editing activities of E67Q and E259Q mutants were both retained but impaired to the same extent. This indicates that the enzymatic activity of this protein is essential but not a sole determinant of the antiviral activity. Furthermore, all the deletion mutants tested in this study lost the antiviral activity because of the loss of the activity for dimerization, suggesting that the entire protein structure is necessary for the antiviral function.
authors.affiliation: Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, 54 Shogoin-Kawaracho, Sakyo-ku, Kyoto 606-8507, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Shindo
authors.forename: Akifumi
authors.initials: A
authors.lastname: Takaori-Kondo
authors.forename: Masayuki
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Aierken
authors.initials: A
authors.lastname: Abudu
authors.forename: Keiko
authors.initials: K
authors.lastname: Fukunaga
authors.forename: Takashi
authors.initials: T
authors.lastname: Uchiyama
mesh_terms: D000071480:APOBEC-3G Deaminase; D000998:Antiviral Agents / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D003564:Cytidine Deaminase / Q000378:metabolism; D004247:DNA / Q000737:chemistry; D019281:Dimerization; D017353:Gene Deletion; D015870:Gene Expression; D015497:HIV-1 / Q000472:pathogenicity*; D006801:Humans; D007163:Immunosorbent Techniques; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009700:Nucleoside Deaminases; D017354:Point Mutation; D011506:Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D017393:RNA Editing; D012097:Repressor Proteins; D013329:Structure-Activity Relationship; D014162:Transfection
chemical_list: D000998:Antiviral Agents; D011506:Proteins; D012097:Repressor Proteins; D004247:DNA; D009700:Nucleoside Deaminases; D000071480:APOBEC-3G Deaminase; C464924:APOBEC3G protein, human; D003564:Cytidine Deaminase