Structure of the cytosine–cytosine mismatch in the thymidylate synthase mRNA binding site and analysis of its interaction with the aminoglycoside paromomycin

(A) Superposition of the 10 lowest energy structures of TSMC. The structures are represented in stick form with adenine nucleotides colored red, guanine nucleotides colored green, and cytosine nucleotides colored blue. All heavy atoms were used for the superposition. (B) Structure of the C5–C16 mismatched base pair. The dotted line indicates the putative hydrogen bond between C5 NH42 and C16 N3.