Mutational specificity of thymine deprivation-induced mutation in the lacI gene of Escherichia coli.
LacI- mutants obtained following 2 and 6 h of thymine deprivation were cloned and sequenced. The mutational spectra recovered were dissimilar. After 2 h of starvation the majority of mutations were base substitutions, largely G:C----C:G transversions. Frameshift mutations but not deletions were observed. In contrast, following 6 h of starvation, with the exception of the G:C----C:G transversion, all possible base substitutions were recovered. Moreover, several deletions but no frameshift events were observed. The differences in the mutational spectra recovered after the two periods of thymine deprivation highlight the role of altered nucleotide pools and the potential influence of DNA replication and repair mechanisms.
Glickman
B W
BW
Department of Biology, York University, Toronto, Ont., Canada.
Allen
F L
FL
Horsfall
M J
MJ
D001483:Base Sequence; D002872:Chromosome Deletion; D004252:DNA Mutational Analysis; D004260:DNA Repair; D004261:DNA Replication; D004926:Escherichia coli / Q000235:genetics*; D007763:Lac Operon; D009154:Mutation; D013941:Thymine / Q000172:deficiency*; D013997:Time Factors
D013941:Thymine