Abstract
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.