DNA Base Pair Mismatches Induce Structural Changes and Alter the Free-Energy Landscape of Base Flip

Double-stranded DNA may contain mismatched base pairs beyond the Watson-Crick pairs, guanine-cytosine and adenine-thymine. Such mismatches bear adverse consequences for human health. We utilize molecular dynamics and metadynamics computer simulations to study the structure and dynamics of both matched and mismatched base pairs. We discover significant differences between the matched and mismatched pairs in structure and base flip work profiles. Mismatched pairs shift more in the plane normal to the DNA strand and exhibit more noncanonical structures, including the e-motif. We discuss the potential implications on the mismatch repair enzymes' detection of DNA mismatches.