"Action-at-a-distance" mutagenesis. 8-oxo-7, 8-dihydro-2'-deoxyguanosine causes base substitution errors at neighboring template sites when copied by DNA polymerase beta.
8-Oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG), a common oxidative DNA lesion, favors a syn-conformation in DNA, enabling formation of stable 8-oxo-dG.A base mispairs resulting in G.C --> T.A transversion mutations. When human DNA polymerase (pol) beta was used to copy a short single-stranded gap containing a site-directed 8-oxo-dG lesion, incorporation of dAMP opposite 8-oxo-dG was slightly favored over dCMP depending on "downstream" sequence context. Unexpectedly, however, a significant increase in dCMP.A and dGMP.A mispairs was also observed at the "upstream" 3'-template site adjacent to the lesion. Errors at these undamaged template sites occurred in four sequence contexts with both gapped and primed single-stranded DNA templates, but not when pol alpha replaced pol beta. Error rates at sites adjacent to 8-oxo-dG were roughly 1% of the values opposite 8-oxo-dG, potentially generating tandem mutations during in vivo short-gap repair synthesis by pol beta. When 8-oxo-dG was replaced with 8-bromo-2'-deoxyguanosine, incorporation of dCMP was strongly favored by both enzymes, with no detectable misincorporation occurring at neighboring template sites.
Efrati
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E
Departments of Biological Sciences and Chemistry, Hedco Molecular Biology Laboratories, University of Southern California, Los Angeles, California 90089-1340, USA.
Tocco
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G
Eritja
R
R
Wilson
S H
SH
Goodman
M F
MF
D000080242:8-Hydroxy-2'-Deoxyguanosine; D020029:Base Pairing / Q000235:genetics; D004247:DNA / Q000737:chemistry; D004249:DNA Damage / Q000235:genetics; D004256:DNA Polymerase I / Q000378:metabolism; D019951:DNA Polymerase beta / Q000378:metabolism*; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D006151:Guanosine / Q000031:analogs & derivatives; D006801:Humans; D007700:Kinetics; D016296:Mutagenesis / Q000235:genetics*; D009154:Mutation / Q000235:genetics; D009690:Nucleic Acid Conformation; D009711:Nucleotides / Q000378:metabolism; D013698:Templates, Genetic
D009711:Nucleotides; D006151:Guanosine; D000080242:8-Hydroxy-2'-Deoxyguanosine; D004247:DNA; D004256:DNA Polymerase I; D019951:DNA Polymerase beta; D003849:Deoxyguanosine