The NarI sequence (5'-G1G2CG3CC-3') is a well-known hot spot for frameshift mutation, where arylamine adduction at G3 position exerts high frequency of -2 deletion mutations. Previous studies have shown that 3'-flanking C bulged out with 2-acetylaminofluorene (AAF)-modified G3 produces -2 deletion. In contrast, 5'-C to the non-acetylated aminofluorene (AF) at G3 was bulged out. Here, we studied lesion-induced -2 bulge structures using pyrrolo-deoxycytidine (PC) as a fluorescent tag.  We used two 16mer templates (5'--G1G2PCG3CC--3' and 5'--G1G2CG3PCC--3') with PC positioned either at 5' or 3' to the lesion site G3. Results suggest that (i) -2 deletion occurs with 3'-PC and G3-AAF involved in bulge formation and (ii) 5'- PC loops out along with G3 in unmodified case.  Similar studies were conducted with AF and 4-aminobiphenyl (ABP) and the results are analyzed in terms of lesion stacking ability and the stability of bulge structures.

Fluorescence probing of the 5' vs. 3' flanking cytosine in arylamine induced -2 bulge structures

244th National Meeting (2012)

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