Fig. 4.
Crystal structure and MD simulations of TDG and A145G-TDG with G·T and G·U substrates. (A) To illustrate the potential steric clash of the methyl groups from dT and Ala145, dU from the TDG-G·UF structure was replaced with dT (interactions shown are from TDG-G·UF structure). The remaining panels are representative structures from the MD simulations, which were selected using the 2D distance plots for active-site interactions (Fig. S3). (B) TDG-G·T with a partially flipped dT nucleotide; (C) TDG-G·T with fully flipped dT, as indicated by interactions seen in the TDG-G·UF crystal structure; (D) A145G-TDG with G·T exhibits complete flipping and active-site contacts; (E) TDG-G·U illustrates complete nucleotide flipping.