title: The retroviral hypermutation specificity of APOBEC3F and APOBEC3G is governed by the C-terminal DNA cytosine deaminase domain.
abstract: The human proteins APOBEC3F and APOBEC3G restrict retroviral infection by deaminating cytosine residues in the first cDNA strand of a replicating virus. These proteins have two putative deaminase domains, and it is unclear whether one or both catalyze deamination, unlike their homologs, AID and APOBEC1, which are well characterized single domain deaminases. Here, we show that only the C-terminal cytosine deaminase domain of APOBEC3F and -3G governs retroviral hypermutation. A chimeric protein with the N-terminal cytosine deaminase domain from APOBEC3G and the C-terminal cytosine deaminase domain from APOBEC3F elicited a dinucleotide hypermutation preference nearly indistinguishable from that of APOBEC3F. This 5'-TC-->TT mutational specificity was confirmed in a heterologous Escherichia coli-based mutation assay, in which the 5'-CC-->CT dinucleotide hypermutation preference of APOBEC3G also mapped to the C-terminal deaminase domain. An N-terminal APOBEC3G deletion mutant displayed a preference indistinguishable from that of the full-length protein, and replacing the C-terminal deaminase domain of APOBEC3F with AID resulted in an AID-like mutational signature. Together, these data indicate that only the C-terminal domain of APOBEC3F and -3G dictates the retroviral minus strand 5'-TC and 5'-CC dinucleotide hypermutation preferences, respectively, leaving the N-terminal domain to perform other aspects of retroviral restriction.
authors.affiliation: University of Minnesota, Department of Biochemistry, Molecular Biology and Biophysics and the Institute for Molecular Virology, Minneapolis, Minnesota 55455, USA.
authors.forename: Guylaine
authors.initials: G
authors.lastname: Haché
authors.forename: Mark T
authors.initials: MT
authors.lastname: Liddament
authors.forename: Reuben S
authors.initials: RS
authors.lastname: Harris
mesh_terms: D000071480:APOBEC-3G Deaminase; D001483:Base Sequence; D003564:Cytidine Deaminase; D043525:Cytosine Deaminase / Q000737:chemistry* / Q000502:physiology; D008969:Molecular Sequence Data; D009154:Mutation; D009700:Nucleoside Deaminases; D011506:Proteins / Q000737:chemistry* / Q000502:physiology; D012097:Repressor Proteins; D012190:Retroviridae / Q000235:genetics*
chemical_list: D011506:Proteins; D012097:Repressor Proteins; D009700:Nucleoside Deaminases; C492906:APOBEC3F protein, human; D043525:Cytosine Deaminase; D000071480:APOBEC-3G Deaminase; C464924:APOBEC3G protein, human; D003564:Cytidine Deaminase