Extensive mutagenesis experiments corroborate a structural model for the DNA deaminase domain of APOBEC3G

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Abstract
APOBEC3G is a single‐strand DNA cytosine deaminase capable of blocking retrovirus and retrotransposon replication. APOBEC3G has two conserved zinc‐coordinating motifs but only one is required for catalysis. Here, deletion analyses revealed that the minimal catalytic domain consists of residues 198‐384. Size exclusion assays indicated that this protein is monomeric. Many (31/69) alanine substitution derivatives of APOBEC3G198‐384 retained significant to full levels of activity. These data corroborated an APOBEC2‐based structural model for the catalytic domain of APOBEC3G indicating that most non‐essential residues are solvent accessible and most essential residues cluster within the protein core.