Wang Q P, Kaguni J M
Department of Biochemistry, Michigan State University, East Lansing 48824.
J Bacteriol. 1989 Aug;171(8):4248-53. doi: 10.1128/jb.171.8.4248-4253.1989.
The Escherichia coli rpoH gene encoding sigma 32, which is involved in the heat shock response, is transcribed from as many as four promoters. We have isolated a novel sigma factor of about 24 kilodaltons that allows core RNA polymerase to transcribe preferentially from one of these promoters, rpoH3p. This promoter is known to be regulated by DnaA protein. The sigma 24 factor was isolated from a preparation of RNA polymerase by electroelution from sodium dodecyl sulfate-polyacrylamide gels followed by renaturation. Expression of heat shock proteins is induced by treatments which include those that induce the stringent response. Under such conditions, decreased transcription from rpoH3p and no increase in transcription from other rpoH promoters were observed. This result suggests that induction of heat shock proteins by the stringent response is not mediated by increased transcription of the rpoH gene.
编码参与热休克反应的σ32的大肠杆菌rpoH基因，可从多达四个启动子转录。我们分离出了一种约24千道尔顿的新型σ因子，它能使核心RNA聚合酶优先从这些启动子之一rpoH3p进行转录。已知该启动子受DnaA蛋白调控。通过从十二烷基硫酸钠-聚丙烯酰胺凝胶中电洗脱，然后复性，从RNA聚合酶制剂中分离出了σ24因子。热休克蛋白的表达可由包括诱导严紧反应的处理诱导产生。在这种条件下，观察到rpoH3p的转录减少，而其他rpoH启动子的转录没有增加。这一结果表明，严紧反应诱导热休克蛋白不是由rpoH基因转录增加介导的。
