Correlation between the 32-kDa sigma factor levels and in vitro expression of Escherichia coli heat shock genes.
S-30 extracts from Escherichia coli cells were used to express heat shock (HS) and non-HS genes in vitro in a DNA-directed protein synthesis system. The S-30 extracts prepared from cells that have been shifted to 45 degrees C express HS genes in vitro approximately 8 times better than extracts from cells at 33 degrees C. In contrast, the expression of non-HS genes in extracts from heat-induced cells is only 40% of that seen in extracts from cells at 33 degrees C. These results correlate well with the levels of HS sigma factor and normal sigma factor bound to RNA polymerase. Thus, there was an 8-fold increase in the HS sigma factor and a 60% decrease in the normal sigma factor associated with RNA polymerase at the higher temperature. Part of the increase in the level of the HS sigma factor could be accounted for by a 3-fold increase in the level of HS sigma factor mRNA during heat induction.
Skelly
S
S
Roche Institute of Molecular Biology, Roche Research Center, Nutley, NJ 07110.
Coleman
T
T
Fu
C F
CF
Brot
N
N
Weissbach
H
H
D012321:DNA-Directed RNA Polymerases / Q000502:physiology; D004926:Escherichia coli / Q000235:genetics*; D005786:Gene Expression Regulation; D006360:Heat-Shock Proteins / Q000235:genetics*; D006358:Hot Temperature; D007163:Immunosorbent Techniques; D066298:In Vitro Techniques; D012808:Sigma Factor / Q000276:immunology / Q000502:physiology*; D014157:Transcription Factors / Q000502:physiology*
D006360:Heat-Shock Proteins; D012808:Sigma Factor; D014157:Transcription Factors; D012321:DNA-Directed RNA Polymerases