DNA Polymerase ν Rapidly Bypasses O 6‑Methyl-dG but Not O 6‑[4-(3-Pyridyl)-4-oxobutyl-dG and O 2‑Alkyl-dTs

• Published in: Chemical research in toxicology 2016-11, Vol.29 (11), p.1894-1900
• Main Authors: Gowda, A. S. Prakasha, Spratt, Thomas E
• Format: Article
• Language: English
• Subjects: Deoxyguanosine - analogs & derivatives; Deoxyguanosine - metabolism; DNA-Directed DNA Polymerase - metabolism; Escherichia coli Proteins - metabolism; Kinetics; Thymidine - metabolism
• ISSN: 0893-228X; 1520-5010
• DOI: 10.1021/acs.chemrestox.6b00318

4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is a potent tobacco carcinogen that forms mutagenic DNA adducts including O 6-methyl-2′-deoxyguanosine (O 6-Me-dG), O 6-[4-(3-pyridyl)-4-oxobut-1-yl]-dG (O 6-POB-dG), O 2-methylthymidine (O 2-Me-dT), and O 2-POB-dT. We evaluated the ability of human DNA polymerase ν to bypass this damage to evaluate the structural constraints on substrates for pol ν and to evaluate if there is kinetic evidence suggesting the in vivo activity of pol ν on tobacco-induced DNA damage. Presteady-state kinetic analysis has indicated that O 6-Me-dG is a good substrate for pol ν, while O 6-POB-dG and the O 2-alkyl-dT adducts are poor substrates for pol ν. The reactivity with O 6-Me-dG is high with a preference for dCTP > dGTP > dATP > dTTP. The catalytic activity of pol ν toward O 6-Me-dG is high and can potentially be involved in its bypass in vivo. In contrast, pol ν is unlikely to bypass O 6-POB-dG or the O 2-alkyl-dTs in vivo.