Specificity of recA441-mediated (tif-1) mutational events.
To investigate the impact of SOS induction on the distribution of spontaneous mutation, 111 recA441-mediated mutations were characterized at the DNA sequence level in the lacI gene of Escherichia coli. A 2.6-fold enhancement in lacI- mutation frequency was observed after induction of the SOS system in the absence of mutagenic treatment, and specific classes of mutational events were induced. G:C----C:G, G:C----T:A and A:T----T:A transversion events were specifically enhanced after SOS induction. A preferential 5'-Y-Purine-3' neighbouring base specificity for these transversion events is reported here (normalised for mutation of the purine residue). In addition, a preference for transversion events at 5'-C/GTGG-3' sequences is also observed. Fifty events were recovered at the lacI "frameshift hotspot site" and were equally represented by 4 bp addition and deletion events. This 1:1 ratio deviates significantly from the 4:1 distribution characteristic of spontaneous frameshift mutation in the RecA+ background and is a consequence of the fourfold induction of the (-)4 event. This abberrant distribution was confirmed by oligomeric probing of 474 independent recA441-mediated spontaneous lacI- mutations.
Yatagai
F
F
Department of Biology, York University, Toronto, Ontario, Canada.
Halliday
J A
JA
Glickman
B W
BW
D000596:Amino Acids / Q000235:genetics; D001483:Base Sequence; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics*; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D009154:Mutation; D011938:Rec A Recombinases; D013014:SOS Response, Genetics; D013379:Substrate Specificity
D000596:Amino Acids; D004269:DNA, Bacterial; D011938:Rec A Recombinases