title: Aprataxin resolves adenylated RNA-DNA junctions to maintain genome integrity.
abstract: Faithful maintenance and propagation of eukaryotic genomes is ensured by three-step DNA ligation reactions used by ATP-dependent DNA ligases. Paradoxically, when DNA ligases encounter nicked DNA structures with abnormal DNA termini, DNA ligase catalytic activity can generate and/or exacerbate DNA damage through abortive ligation that produces chemically adducted, toxic 5'-adenylated (5'-AMP) DNA lesions. Aprataxin (APTX) reverses DNA adenylation but the context for deadenylation repair is unclear. Here we examine the importance of APTX to RNase-H2-dependent excision repair (RER) of a lesion that is very frequently introduced into DNA, a ribonucleotide. We show that ligases generate adenylated 5' ends containing a ribose characteristic of RNase H2 incision. APTX efficiently repairs adenylated RNA-DNA, and acting in an RNA-DNA damage response (RDDR), promotes cellular survival and prevents S-phase checkpoint activation in budding yeast undergoing RER. Structure-function studies of human APTX-RNA-DNA-AMP-Zn complexes define a mechanism for detecting and reversing adenylation at RNA-DNA junctions. This involves A-form RNA binding, proper protein folding and conformational changes, all of which are affected by heritable APTX mutations in ataxia with oculomotor apraxia 1. Together, these results indicate that accumulation of adenylated RNA-DNA may contribute to neurological disease.
authors.affiliation: 1] Laboratory of Structural Biology, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, North Carolina 27709, USA [2].
authors.forename: Percy
authors.initials: P
authors.lastname: Tumbale
authors.affiliation: 1] Laboratory of Structural Biology, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, North Carolina 27709, USA [2] Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, North Carolina 27709, USA [3].
authors.forename: Jessica S
authors.initials: JS
authors.lastname: Williams
authors.affiliation: 1] Laboratory of Structural Biology, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, North Carolina 27709, USA [2].
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Schellenberg
authors.affiliation: 1] Laboratory of Structural Biology, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, North Carolina 27709, USA [2] Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, North Carolina 27709, USA.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Kunkel
authors.affiliation: Laboratory of Structural Biology, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, North Carolina 27709, USA.
authors.forename: R Scott
authors.initials: RS
authors.lastname: Williams
mesh_terms: D000249:Adenosine Monophosphate / Q000378:metabolism; D001072:Apraxias / Q000235:genetics; D001260:Ataxia Telangiectasia / Q000235:genetics; D002470:Cell Survival; D002524:Cerebellar Ataxia / Q000151:congenital; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005090:Exodeoxyribonucleases / Q000737:chemistry / Q000378:metabolism; D015894:Genome, Human / Q000235:genetics*; D006801:Humans; D034141:Hypoalbuminemia / Q000235:genetics; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009690:Nucleic Acid Conformation; D011487:Protein Conformation; D017510:Protein Folding; D012313:RNA / Q000737:chemistry / Q000378:metabolism*; D016914:Ribonuclease H / Q000378:metabolism; D059807:S Phase Cell Cycle Checkpoints; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D012568:Schizosaccharomyces / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry / Q000378:metabolism; D013329:Structure-Activity Relationship; D015032:Zinc / Q000378:metabolism
chemical_list: C438188:APTX protein, human; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D029702:Schizosaccharomyces pombe Proteins; D000249:Adenosine Monophosphate; D012313:RNA; D004247:DNA; D005090:Exodeoxyribonucleases; C569391:Hnt3 protein, S pombe; C091139:ribonuclease HII; D016914:Ribonuclease H; D015032:Zinc