2-amino-3-methylimidazo[4,5-f]quinolone, IQ, is a genotoxic compound most commonly found in cooked meats. Two-base deletions are commonly observed in GC repeat sequences, but appear to be sequence dependent. Structural studies using NMR and CD to look at the N2-IQ-dG in the NarI Recognition sequence (G1G2CG3CC) will aim to provide insight why the base deletions occur at the G3 position, but not at G1 or G2. CD data suggests the perturbations to the duplexes are similar for the three duplexes. Solution NMR structures of the G1 and G3 adducts indicate intercalation of the IQ ring that prevents hydrogen bonding between the opposite base, which is rotated into the major groove to accomodate the adduct. Such a conformation allows the IQ  to modify the duplex without decreasing the thermal stability of duplex due to strong base stacking interactions and likely contributing to its persistance in tissue.

Structural studies of the food mutagen 2-amino-3-methylimidazo[4,5-f]quinolone-dG adduct in the NarI recognition sequence

248th National Meeting (2014)

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