DNA sequence determinants of carcinogen-induced frameshift mutagenesis.
In order to examine the mechanisms of induced frameshift mutagenesis, we constructed double-stranded DNA plasmids which contain single N-2-acetylaminofluorene (AAF) adducts at specified positions within a run of contiguous guanine residues. The length of the homopolymeric run and the nature of the bases flanking the contiguous sequence were systematically varied. Monomodified plasmids were introduced into SOS-induced Escherichia coli, and -1 frameshift mutations were scored by means of a phenotypic assay. A strong positional effect of the DNA adduct within the contiguous sequence was observed irregardless of the nature of the flanking bases: the AAF-induced mutation frequency was 20-200-fold higher at the 3'-end of the contiguous sequence than at the 5'-end. In addition, for a given number of guanine residues flanking the GAAF adduct on its 5'-side, differences (up to 5-fold) in the induced mutation frequency were observed as a function of the base 3' to the adduct (CGGGAAFAT approximately CGGGAAFGT > CGGGAAFCT > CGGGAAFTT). These results are discussed, within the frame of an incorporation slippage model, in terms of differences in stability and occurrence of the slipped mutagenic intermediates.
Napolitano
R L
RL
UPR Cancérogenèse et Mutagenèse Moléculaire et Structurale, CNRS, IBMC, Strasbourg, France.
Lambert
I B
IB
Fuchs
R P
RP
D015073:2-Acetylaminofluorene / Q000494:pharmacology; D001483:Base Sequence; D004247:DNA / Q000737:chemistry* / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D016368:Frameshift Mutation; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010957:Plasmids; D013014:SOS Response, Genetics
D004247:DNA; D015073:2-Acetylaminofluorene