RNase H overproduction allows the expression of stress-induced genes in the absence of topoisomerase I.
Induction of stress proteins in response to heat shock was found to be reduced significantly in Escherichia coli with DeltatopA mutation. RNase H overexpression in the DeltatopA mutant partially restored the sigma(32)-dependent induction of stress genes in response to high temperature and ethanol. The presence of overexpressed RNase H also improved the survival rate of the DeltatopA mutant after high temperature and oxidative challenges. Topoisomerase I is likely required during stress response for preventing accumulation of transcription-driven hypernegative supercoiling and R-loop formation at induced stress genes loci.
Cheng
Bokun
B
Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, NY 10595, USA.
Rui
Shan
S
Ji
Chengling
C
Gong
Vivien W
VW
Van Dyk
Tina K
TK
Drolet
Marc
M
Tse-Dinh
Yuk-Ching
YC
D004264:DNA Topoisomerases, Type I / Q000235:genetics*; D004269:DNA, Bacterial / Q000032:analysis; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D015964:Gene Expression Regulation, Bacterial; D006360:Heat-Shock Proteins / Q000096:biosynthesis*; D009154:Mutation; D009690:Nucleic Acid Conformation; D016914:Ribonuclease H / Q000096:biosynthesis*; D013696:Temperature; D014158:Transcription, Genetic
D004269:DNA, Bacterial; D006360:Heat-Shock Proteins; D016914:Ribonuclease H; D004264:DNA Topoisomerases, Type I