title: Translesion synthesis past equine estrogen-derived 2'-deoxycytidine DNA adducts by human DNA polymerases eta and kappa.
abstract: Estrogen replacement therapy (ERT), composed of equilenin, is associated with increased risk of breast, ovarian, and endometrial cancers. Several diastereoisomers of unique dC and dA DNA adducts were derived from 4-hydroxyequilenin (4-OHEN), a metabolite of equilenin, and have been detected in women receiving ERT. To explore the miscoding property of 4-OHEN-dC adduct, site-specifically modified oligodeoxynucleotides (Pk-1, Pk-2, Pk-3, and Pk-4) containing a single diastereoisomer of 4-OHEN-dC were prepared by a postsynthetic method. Among them, major 4-OHEN-dC-modified oligodeoxynucleotides (Pk-3 and Pk-4) were used to prepare the templates for primer extension reactions catalyzed by DNA polymerase (pol) alpha, pol eta, and pol kappa. Primer extension was retarded one base prior to the lesion and opposite the lesion; stronger blockage was observed with pol alpha, while with human pol eta or pol kappa, a fraction of the primers was extended past the lesion. Steady-state kinetic studies showed that both pol kappa and pol eta inserted dCMP and dAMP opposite the 4-OHEN-dC and extended past the lesion. Never or less-frequently, dGMP, the correct base, was inserted opposite the lesion. The relative bypass frequency past the 4-OHEN-dC lesion with pol eta was at least 3 orders of magnitude higher than that for pol kappa, as observed for primer extension reactions. The bypass frequency past the dA.4-OHEN-dC adduct in Pk-4 was 2 orders of magnitude more efficient than that past the adduct in Pk-3. Thus, 4-OHEN-dC is a highly miscoding lesion capable of generating C --> T transitions and C --> G transversions. The miscoding frequency and specificity of 4-OHEN-dC were strikingly influenced by the adduct stereochemistry and DNA polymerase used.
authors.affiliation: Laboratory of Chemical Biology, Department of Pharmacological Sciences, State University of New York at Stony Brook, Stony Brook, New York 11794-8651, USA.
authors.forename: Naomi
authors.initials: N
authors.lastname: Suzuki
authors.forename: Manabu
authors.initials: M
authors.lastname: Yasui
authors.forename: Y R
authors.initials: YR
authors.lastname: Santosh Laxmi
authors.forename: Haruo
authors.initials: H
authors.lastname: Ohmori
authors.forename: Fumio
authors.initials: F
authors.lastname: Hanaoka
authors.forename: Shinya
authors.initials: S
authors.lastname: Shibutani
mesh_terms: D000818:Animals; D020137:Base Pair Mismatch / Q000235:genetics; D004247:DNA / Q000737:chemistry / Q000235:genetics; D018736:DNA Adducts / Q000737:chemistry* / Q000235:genetics; D004249:DNA Damage / Q000235:genetics; D004259:DNA-Directed DNA Polymerase / Q000737:chemistry* / Q000235:genetics; D003841:Deoxycytidine / Q000737:chemistry* / Q000235:genetics; D004855:Equilenin / Q000031:analogs & derivatives* / Q000737:chemistry* / Q000235:genetics; D004857:Equilin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000235:genetics; D006736:Horses; D006801:Humans; D007700:Kinetics; D016297:Mutagenesis, Site-Directed; D009838:Oligodeoxyribonucleotides / Q000138:chemical synthesis / Q000235:genetics; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013237:Stereoisomerism; D013698:Templates, Genetic; D000099270:Y-Family DNA Polymerases
chemical_list: D004247:DNA; D018736:DNA Adducts; D004259:DNA-Directed DNA Polymerase; D003841:Deoxycytidine; D004855:Equilenin; D004857:Equilin; D009838:Oligodeoxyribonucleotides; C065250:4-hydroxy-equilenin; C065248:4-hydroxy-equilin; C427203:calf thymus DNA; C404302:POLK protein, human; D000099270:Y-Family DNA Polymerases; C112338:Rad30 protein