Effect of Size and Shape of Nitrogen-Containing Aromatics on Conformational Preferences of DNA Containing Damaged Guanine.

The present work investigates the effects of the size and shape of the nitrogen-containing aromatic (NCA) skeleton on the structure of DNA damaged through adduct formation at C8 of 2'-deoxyguanosine (dG), a common DNA lesion associated with chemical carcinogenesis. Specifically, density functional theory (DFT) calculations (B3LYP-D3) and molecular dynamics (MD) simulations (AMBER) are performed on seven model adducts with systematic expansion of the NCA moiety. DFT calculations reveal that the NCA moiety shape affects the structure at the nucleobase-carcinogen linkage. Approximately 4.5 μs of MD simulations on damaged oligonucleotides adopting three established conformational themes (namely, B, W, and S) illustrate that the structure and lesion-site stabilization strongly depend on the NCA moiety shape and size, which provides insight into the repair propensity of C8-dG adducted DNA. Our results add bulky moiety shape to the growing list of previously established effects on the conformational and repair outcomes of damaged DNA (i.e., size, ionization state, substitution, linker type, and DNA sequence). Furthermore, this work illustrates the utility of a systematic set of model DNA lesions for understanding the structure-activity relationship for DNA damaged by carcinogens of different sizes and shapes, which should be used in future studies of the cellular processing of damaged DNA.