Increased thermosensitivity associated with topoisomerase I deletion and promoter mutations in Escherichia coli.
An Escherichia coli mutant with three of the promoters for the topoisomerase I gene (topA) deleted, such that only the sigma 32-dependent promoter (P1) remained, had a decreased level of topoisomerase I at 30 degrees C and showed increased thermosensitivity at 52 degrees C. However, it could still develop thermotolerance and had a wild-type level of resistance to 52 degrees C treatment if exposed first to 42 degrees C. This indicated that newly synthesized topoisomerase I from transcription initiated at P1 was important for development of thermotolerance. Two other E. coli mutants lacking topA were > 100 times more sensitive to high temperature than their wild-type isogenic strains.
Qi
H
H
Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla 10595, USA.
Menzel
R
R
Tse-Dinh
Y C
YC
D004264:DNA Topoisomerases, Type I / Q000235:genetics*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D017353:Gene Deletion; D005798:Genes, Bacterial / Q000235:genetics; D005838:Genotype; D006358:Hot Temperature; D009154:Mutation; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012808:Sigma Factor / Q000235:genetics
D012808:Sigma Factor; D004264:DNA Topoisomerases, Type I