title: NMR structure of human restriction factor APOBEC3A reveals substrate binding and enzyme specificity.
abstract: Human APOBEC3A is a single-stranded DNA cytidine deaminase that restricts viral pathogens and endogenous retrotransposons, and has a role in the innate immune response. Furthermore, its potential to act as a genomic DNA mutator has implications for a role in carcinogenesis. A deeper understanding of APOBEC3A's deaminase and nucleic acid-binding properties, which is central to its biological activities, has been limited by the lack of structural information. Here we report the nuclear magnetic resonance solution structure of APOBEC3A and show that the critical interface for interaction with single-stranded DNA substrates includes residues extending beyond the catalytic centre. Importantly, by monitoring deaminase activity in real time, we find that A3A displays similar catalytic activity on APOBEC3A-specific TTCA- or A3G-specific CCCA-containing substrates, involving key determinants immediately 5' of the reactive C. Our results afford novel mechanistic insights into APOBEC3A-mediated deamination and provide the structural basis for further molecular studies.
authors.affiliation: Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 Fifth Avenue, Pittsburgh, PA 15261, USA.
authors.forename: In-Ja L
authors.initials: IJ
authors.lastname: Byeon
authors.forename: Jinwoo
authors.initials: J
authors.lastname: Ahn
authors.forename: Mithun
authors.initials: M
authors.lastname: Mitra
authors.forename: Chang-Hyeock
authors.initials: CH
authors.lastname: Byeon
authors.forename: Kamil
authors.initials: K
authors.lastname: Hercík
authors.forename: Jozef
authors.initials: J
authors.lastname: Hritz
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Charlton
authors.forename: Judith G
authors.initials: JG
authors.lastname: Levin
authors.forename: Angela M
authors.initials: AM
authors.lastname: Gronenborn
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D055162:Biocatalysis; D003564:Cytidine Deaminase / Q000737:chemistry* / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D003641:Deamination; D003845:Deoxycytosine Nucleotides / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism*; D012313:RNA / Q000378:metabolism; D012996:Solutions; D013379:Substrate Specificity; D014544:Uridine Triphosphate / Q000378:metabolism
chemical_list: D003845:Deoxycytosine Nucleotides; D011506:Proteins; D012996:Solutions; C024107:2'-deoxycytidine 5'-triphosphate; D012313:RNA; D004247:DNA; C121399:APOBEC3A protein, human; D003564:Cytidine Deaminase; D014544:Uridine Triphosphate