title: Effects of SOS and MucAB functions on reactivation and mutagenesis of M13 replicative form DNA bearing bulky lesions.
abstract: We have previously determined the specificity of -1 frameshifts induced by aflatoxin-B1-2,3-dichloride (AFB1C12) in phage M13 double-strand replicative form (RF) DNA. The system consists of: (i) in vitro adduction of RF DNA of BK8, a lacZ + 1 frameshift derivative of phage M13mp8; (ii) transfection into unirradiated or UV-irradiated bacterial host cells; (iii) scoring and sequencing of revertants (i.e., -1 frameshifts). The previous data had shown that induction of SOS functions enhanced mutagenesis. However, this increase in mutagenesis is not accompanied by enhanced survival in a majority of the strains tested. Here, we present evidence to show that the lack of SOS reactivation is a specific property of the RF DNA system rather than a specific property of the lesion. A model mechanism based on the replicative strategy of transfected RF DNA can account for these observations. In addition, we have calculated individual Weigle mutagenesis factors at 8 major mutagen induced sites reported previously. Analysis of these data indicates that, within a restricted subset of possible mutational events (i.e., -1 frameshifts), Weigle mutagenesis is affected by both the DNA sequence environment of the mutation site as well as the repair phenotype of the cell.
mesh_terms: D016604:Aflatoxin B1; D000348:Aflatoxins; D001483:Base Sequence; D003090:Coliphages / Q000235:genetics*; D004249:DNA Damage; D004260:DNA Repair; D004261:DNA Replication; D004279:DNA, Viral / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics*; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D013014:SOS Response, Genetics; D001616:beta-Galactosidase / Q000235:genetics
chemical_list: D000348:Aflatoxins; D004279:DNA, Viral; D016604:Aflatoxin B1; D001616:beta-Galactosidase