title: APOBEC3G is a single-stranded DNA cytidine deaminase and functions independently of HIV reverse transcriptase.
abstract: In the absence of the viral vif gene, human immunodeficiency virus (HIV) may be restricted by the APOBEC3G gene on chromosome 22. The role of the HIV Vif protein is to exclude host cell APOBEC3G from the budding virion. As APOBEC3G shows sequence homology to cytidine deaminases, it is presumed that in the absence of Vif, cytidine residues in the cDNA are deaminated yielding uracil. It is not known if additional proteins mediate APOBEC3G function or if deamination occurs in concert with reverse transcription. This report describes an in vitro assay showing that Baculovirus derived APOBEC3G alone extensively deaminates cDNA independently of reverse transcriptase. It reproduces the dinucleotide context typical of G --> A hypermutants derived from a Delta(vif) virus. By using an RNaseH- form of reverse transcriptase, it was shown that the cDNA has to be free of its RNA template to allow deamination. APOBEC3G deamination of dC or dCTP was not detected. In short, APOBEC3G is a single-stranded DNA cytidine deaminase capable of restricting retroviral replication.
authors.affiliation: Unité de Rétrovirologie Moléculaire, Institut Pasteur, 28 rue du Docteur Roux, 75724 Paris cedex 15, France.
authors.forename: Rodolphe
authors.initials: R
authors.lastname: Suspène
authors.forename: Peter
authors.initials: P
authors.lastname: Sommer
authors.forename: Michel
authors.initials: M
authors.lastname: Henry
authors.forename: Stéphane
authors.initials: S
authors.lastname: Ferris
authors.forename: Denise
authors.initials: D
authors.lastname: Guétard
authors.forename: Sylvie
authors.initials: S
authors.lastname: Pochet
authors.forename: Ann
authors.initials: A
authors.lastname: Chester
authors.forename: Naveenan
authors.initials: N
authors.lastname: Navaratnam
authors.forename: Simon
authors.initials: S
authors.lastname: Wain-Hobson
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Vartanian
mesh_terms: D000071480:APOBEC-3G Deaminase; D001483:Base Sequence; D003564:Cytidine Deaminase / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000378:metabolism*; D015226:Dinucleoside Phosphates / Q000378:metabolism; D054303:HIV Reverse Transcriptase / Q000378:metabolism*; D009700:Nucleoside Deaminases; D011506:Proteins / Q000378:metabolism / Q000502:physiology*; D012097:Repressor Proteins; D013379:Substrate Specificity; D014158:Transcription, Genetic
chemical_list: D004277:DNA, Single-Stranded; D015226:Dinucleoside Phosphates; D011506:Proteins; D012097:Repressor Proteins; C015101:cytidylyl-(3'-5')-cytidine; D054303:HIV Reverse Transcriptase; D009700:Nucleoside Deaminases; D000071480:APOBEC-3G Deaminase; C464924:APOBEC3G protein, human; D003564:Cytidine Deaminase