title: In vitro effect of the Escherichia coli heat shock regulatory protein on expression of heat shock genes.
abstract: In Escherichia coli, the ability to elicit a heat shock response depends on the htpR gene product. Previous work has shown that the HtpR protein serves as a sigma factor (sigma 32) for RNA polymerase that specifically recognizes heat shock promoters (A.D. Grossman, J.W. Erickson, and C.A. Gross Cell 38:383-390, 1984). In the present study we showed that sigma 32 synthesized in vitro could stimulate the expression of heat shock genes. The in vitro-synthesized sigma 32 was found to be associated with RNA polymerase. In vivo-synthesized sigma 32 was also associated with RNA polymerase, and this polymerase (E sigma 32) could be isolated free of the standard polymerase (E sigma 70). E sigma 32 was more active than E sigma 70 with heat shock genes; however, non-heat-shock genes were not transcribed by E sigma 32. The in vitro expression of the htpR gene required E sigma 70 but did not require E sigma 32.
mesh_terms: D002850:Chromatography, Gel; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000032:analysis* / Q000235:genetics; D005786:Gene Expression Regulation / Q000187:drug effects*; D006360:Heat-Shock Proteins / Q000235:genetics*; D009876:Operon; D012808:Sigma Factor / Q000378:metabolism
chemical_list: D006360:Heat-Shock Proteins; D012808:Sigma Factor; D012321:DNA-Directed RNA Polymerases