title: In vivo detection and replication studies of α-anomeric lesions of 2'-deoxyribonucleosides.
abstract: DNA damage, arising from endogenous metabolism or exposure to environmental agents, may perturb the transmission of genetic information by blocking DNA replication and/or inducing mutations, which contribute to the development of cancer and likely other human diseases. Hydroxyl radical attack on the C1', C3' and C4' of 2-deoxyribose can give rise to epimeric 2-deoxyribose lesions, for which the in vivo occurrence and biological consequences remain largely unexplored. Through independent chemical syntheses of all three epimeric lesions of 2'-deoxyguanosine (dG) and liquid chromatography-tandem mass spectrometry analysis, we demonstrated unambiguously the presence of substantial levels of the α-anomer of dG (α-dG) in calf thymus DNA and in DNA isolated from mouse pancreatic tissues. We further assessed quantitatively the impact of all four α-dN lesions on DNA replication in Escherichia coli by employing a shuttle-vector method. We found that, without SOS induction, all α-dN lesions except α-dA strongly blocked DNA replication and, while replication across α-dA was error-free, replicative bypass of α-dC and α-dG yielded mainly C→A and G→A mutations. In addition, SOS induction could lead to markedly elevated bypass efficiencies for the four α-dN lesions, abolished the G→A mutation for α-dG, pronouncedly reduced the C→A mutation for α-dC and triggered T→A mutation for α-dT. The preferential misincorporation of dTMP opposite the α-dNs could be attributed to the unique base-pairing properties of the nucleobases elicited by the inversion of the configuration of the N-glycosidic linkage. Our results also revealed that Pol V played a major role in bypassing α-dC, α-dG and α-dT in vivo. The abundance of α-dG in mammalian tissue and the impact of the α-dNs on DNA replication demonstrate for the first time the biological significance of this family of DNA lesions.
authors.affiliation: Department of Chemistry, University of California, Riverside, CA 92521, USA.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Amato
authors.affiliation: Department of Chemistry, University of California, Riverside, CA 92521, USA Department of Chemistry, College of Science, Huazhong Agricultural University, Wuhan, 430070, China.
authors.forename: Qianqian
authors.initials: Q
authors.lastname: Zhai
authors.affiliation: Department of Metabolism and Aging, The Scripps Research Institute Florida, FL 33458, USA.
authors.forename: Diana C
authors.initials: DC
authors.lastname: Navarro
authors.affiliation: Department of Metabolism and Aging, The Scripps Research Institute Florida, FL 33458, USA.
authors.forename: Laura J
authors.initials: LJ
authors.lastname: Niedernhofer
authors.affiliation: Department of Chemistry, University of California, Riverside, CA 92521, USA Yinsheng.Wang@ucr.edu.
authors.forename: Yinsheng
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000818:Animals; D020029:Base Pairing; D004247:DNA / Q000737:chemistry; D004249:DNA Damage; D004261:DNA Replication; D003849:Deoxyguanosine / Q000032:analysis / Q000737:chemistry*; D003853:Deoxyribonucleosides / Q000737:chemistry; D051379:Mice; D016296:Mutagenesis; D013237:Stereoisomerism
chemical_list: D003853:Deoxyribonucleosides; D004247:DNA; C427203:calf thymus DNA; D003849:Deoxyguanosine