Jeong Yun Choi

DNA polymerase (pol) kappa is one of the so-called translesion polymerases involved in replication past DNA lesions. Bypass events have been studied with a number of chemical modifications with human pol kappa, and the conclusion has been presented, based on limited quantitative data, that the enzyme is ineffective at incorporating opposite DNA damage but proficient at extending beyond bases paired with the damage. Purified recombinant full-length human pol kappa was studied with a series of eig

DNA polymerase (pol) iota has been proposed to be involved in translesion synthesis past minor groove DNA adducts via Hoogsteen base pairing. The N2 position of G, located in minor groove side of duplex DNA, is a major site for DNA modification by various carcinogens. Oligonucleotides with varying adduct size at G N2 were analyzed for bypass ability and fidelity with human pol iota. Pol iota effectively bypassed N2-methyl (Me)G and N2-ethyl(Et)G, partially bypassed N2-isobutyl(Ib)G and N2-benzyl

REV1, a Y family DNA polymerase (pol), is involved in replicative bypass past DNA lesions, so-called translesion DNA synthesis. In addition to a structural role as a scaffold protein, REV1 has been proposed to play a catalytic role as a dCTP transferase in translesion DNA synthesis past abasic and guanine lesions in eukaryotes. To better understand the catalytic function of REV1 in guanine lesion bypass, purified recombinant human REV1 was studied with two series of guanine lesions, N(2)-alkylG

1,N(2)-Etheno(epsilon)guanine (epsilon) is formed in DNA as a result of exposure to certain vinyl monomers (e.g., vinyl chloride) or from lipid peroxidation. This lesion has been shown to be mutagenic in bacteria and mammalian cells. 1,N(2)-epsilon-G has been shown to block several model replicative DNA polymerases (pols), with limited bypass. Recently, an archebacterial DNA pol, Sulfolobus solfataricus Dpo4, has been shown to copy past 1,N(2)-epsilon-G. In this study, we examined the abilities

The hyperthermophilic crenarchaeon Sulfolobus solfataricus P2 encodes three B-family DNA polymerase genes, B1 (Dpo1), B2 (Dpo2), and B3 (Dpo3), and one Y-family DNA polymerase gene, Dpo4, which are related to eukaryotic counterparts. Both mRNAs and proteins of all four DNA polymerases were constitutively expressed in all growth phases. Dpo2 and Dpo3 possessed very low DNA polymerase and 3' to 5' exonuclease activities in vitro. Steady-state kinetic efficiencies (k(cat)/K(m)) for correct nucleoti

The N-2 atom of guanine (G) is susceptible to modification by various carcinogens. Oligonucleotides with increasing bulk at this position were analyzed for fidelity and catalytic efficiency with the processive DNA polymerases human immunodeficiency virus, type 1, reverse transcriptase (RT), and bacteriophage T7 exonuclease(-) (T7(-)). RT and T7(-) effectively bypassed N(2)-methyl(Me)G and readily extended primers but were strongly blocked by N(2)-ethyl(Et)G, N(2)-isobutylG, N(2)-benzylG, and N(2

Heterocyclic arylamines are highly mutagenic and cause tumors in animal models. The mutagenicity is attributed to the C8- and N2-G adducts, the latter of which accumulates due to slower repair. The C8- and N 2-G adducts derived from 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) were placed at the G1 and G3 sites of the NarI sequence, in which the G3 site is an established hot spot for frameshift mutation with the model arylamine derivative 2-acetylaminofluorene but G1 is not. Human DNA polymerase