Translesion DNA synthesis across pyrimido[1,2-α]purin-10(3H)-one adduct by human DNA polymerase Pol η

TOXI 117

M. Abul Kalam, m.kalam@vanderbilt.edu1, Carmelo J. Rizzo, c.j.rizzo@vanderbilt.edu2, F. Peter Guengerich3, and Lawrence J. Marnett, larry.marnett@vanderbilt.edu3. (1) A. B. Hancock, Jr. Memorial Laboratory for Cancer Research, Department of Biochemistry, Vanderbilt University, Nashville, TN 37232-0146, (2) Department of Chemistry, Center in Molecular Toxicology and the Vanderbilt-Ingram Cancer Center, Vanderbilt University, Nashville, TN 37235, (3) Department of Biochemistry and Center in Molecular Toxicology, Vanderbilt University School of Medicine, Nashville, TN 37232
3-(2′-Deoxy-β-D-erythro-pentofuranosyl)pyrimido[1,2-α]purin-10(3H)-one (M1dG) is formed in DNA as a result of reaction of deoxyguanosine (dG) with malondialdehyde or base propenals. This lesion has been shown to be mutagenic in bacteria and mammalian cells. M1dG is a strong block to in vitro replication by Klenow fragments of DNA polymerase I. In this study, we examined the ability of recombinant human Y-family DNA polymerase η (pol η) to synthesize across from M1dG. A twenty-three base deoxyoligonucleotide modified with M1dG at fifth position from 5′ end was annealed to an eighteen base primer and used as a template for synthesis. Synthesis by pol η was partially blocked by M1dG but deoxynucleotides were incorporated opposite dG or M1dG following the order dCTP>dGTP>dATP. The misinsertion frequencies of dATP and dGTP, respectively, opposite M1dG were about 100- and 60-times higher than those observed opposite dG. This suggests possible involvement of pol η in G→T and G→C substitutions induced by M1dG in mammalian cells.
 

Poster Session and Awards
6:00 PM-10:00 PM, Tuesday, August 21, 2007 BCEC -- 204 A/B, Poster

Division of Chemical Toxicology

The 234th ACS National Meeting, Boston, MA, August 19-23, 2007