title: Structure of the DNA deaminase domain of the HIV-1 restriction factor APOBEC3G.
abstract: The human APOBEC3G (apolipoprotein B messenger-RNA-editing enzyme, catalytic polypeptide-like 3G) protein is a single-strand DNA deaminase that inhibits the replication of human immunodeficiency virus-1 (HIV-1), other retroviruses and retrotransposons. APOBEC3G anti-viral activity is circumvented by most retroelements, such as through degradation by HIV-1 Vif. APOBEC3G is a member of a family of polynucleotide cytosine deaminases, several of which also target distinct physiological substrates. For instance, APOBEC1 edits APOB mRNA and AID deaminates antibody gene DNA. Although structures of other family members exist, none of these proteins has elicited polynucleotide cytosine deaminase or anti-viral activity. Here we report a solution structure of the human APOBEC3G catalytic domain. Five alpha-helices, including two that form the zinc-coordinating active site, are arranged over a hydrophobic platform consisting of five beta-strands. NMR DNA titration experiments, computational modelling, phylogenetic conservation and Escherichia coli-based activity assays combine to suggest a DNA-binding model in which a brim of positively charged residues positions the target cytosine for catalysis. The structure of the APOBEC3G catalytic domain will help us to understand functions of other family members and interactions that occur with pathogenic proteins such as HIV-1 Vif.
authors.affiliation: Department of Biochemistry, Molecular Biology and Biophysics, [of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Kuan-Ming
authors.initials: KM
authors.lastname: Chen
authors.forename: Elena
authors.initials: E
authors.lastname: Harjes
authors.forename: Phillip J
authors.initials: PJ
authors.lastname: Gross
authors.forename: Amr
authors.initials: A
authors.lastname: Fahmy
authors.forename: Yongjian
authors.initials: Y
authors.lastname: Lu
authors.forename: Keisuke
authors.initials: K
authors.lastname: Shindo
authors.forename: Reuben S
authors.initials: RS
authors.lastname: Harris
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Matsuo
mesh_terms: D000071480:APOBEC-3G Deaminase; D001665:Binding Sites; D002384:Catalysis; D020134:Catalytic Domain; D003564:Cytidine Deaminase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000737:chemistry / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015497:HIV-1 / Q000502:physiology*; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D017433:Protein Structure, Secondary; D015032:Zinc / Q000378:metabolism
chemical_list: D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D000071480:APOBEC-3G Deaminase; C464924:APOBEC3G protein, human; D003564:Cytidine Deaminase; D015032:Zinc