title: Reduced repair capacity of a DNA clustered damage site comprised of 8-oxo-7,8-dihydro-2'-deoxyguanosine and 2-deoxyribonolactone results in an increased mutagenic potential of these lesions.
abstract: A signature of ionizing radiation is the induction of DNA clustered damaged sites. Non-double strand break (DSB) clustered damage has been shown to compromise the base excision repair pathway, extending the lifetimes of the lesions within the cluster, compared to isolated lesions. This increases the likelihood the lesions persist to replication and thus increasing the mutagenic potential of the lesions within the cluster. Lesions formed by ionizing radiation include 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) and 2-deoxyribonolactone (dL). dL poses an additional challenge to the cell as it is not repaired by the short-patch base excision repair pathway. Here we show recalcitrant dL repair is reflected in mutations observed when DNA containing it and a proximal 8-oxodGuo is replicated in Escherichia coli. 8-oxodGuo in close proximity to dL on the opposing DNA strand results in an enhanced frequency of mutation of the lesions within the cluster and a 20 base sequence flanking the clustered damage site in an E. coli based plasmid assay. In vitro repair of a dL lesion is reduced when compared to the repair of an abasic (AP) site and a tetrahydrofuran (THF), and this is due mainly to a reduction in the activity of polymerase β, leading to retarded FEN1 and ligase 1 activities. This study has given insights in to the biological effects of clusters containing dL.
authors.affiliation: CRUK-MRC Gray Institute for Radiation Oncology and Biology, Department of Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford OX3 7DQ, UK.
authors.forename: Siobhan
authors.initials: S
authors.lastname: Cunniffe
authors.affiliation: CRUK-MRC Gray Institute for Radiation Oncology and Biology, Department of Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford OX3 7DQ, UK. Electronic address: peter.oneill@oncology.ox.ac.uk.
authors.forename: Peter
authors.initials: P
authors.lastname: O'Neill
authors.affiliation: Johns Hopkins University, Department of Chemistry, 3400 N. Charles St. , Baltimore, MD 21218, USA.
authors.forename: Marc M
authors.initials: MM
authors.lastname: Greenberg
authors.affiliation: CRUK-MRC Gray Institute for Radiation Oncology and Biology, Department of Oncology, University of Oxford, Old Road Campus Research Building, Roosevelt Drive, Oxford OX3 7DQ, UK.
authors.forename: Martine E
authors.initials: ME
authors.lastname: Lomax
mesh_terms: D000080242:8-Hydroxy-2'-Deoxyguanosine; D001681:Biological Assay; D053903:DNA Breaks, Double-Stranded; D019951:DNA Polymerase beta / Q000235:genetics / Q000378:metabolism; D004260:DNA Repair; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D045585:Flap Endonucleases / Q000235:genetics / Q000378:metabolism; D005663:Furans / Q000737:chemistry / Q000378:metabolism; D005720:Gamma Rays; D015964:Gene Expression Regulation, Bacterial; D016296:Mutagenesis / Q000528:radiation effects*; D009154:Mutation; D010957:Plasmids; D013400:Sugar Acids / Q000737:chemistry / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D005663:Furans; D013400:Sugar Acids; C056405:2,4,5-trihydroxypentanoic acid gamma-lactone; C018674:tetrahydrofuran; D000080242:8-Hydroxy-2'-Deoxyguanosine; D019951:DNA Polymerase beta; D045585:Flap Endonucleases; D003849:Deoxyguanosine
keywords: 2-Deoxyribonolactone; 8-Oxo-7,8-dihydro-2′-deoxyguanosine; Base excision repair; Clustered DNA damage; Mutation; Oxidized abasic sites