The activity of sigma 32 is reduced under conditions of excess heat shock protein production in Escherichia coli.
The activity of sigma 32 is reduced under conditions of excess heat shock protein production in Escherichia coli.
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DOI：
10.1101/gad.3.12a.2003
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发表时间：
1989-12
影响因子：
10.5
通讯作者：
David B. Straus;William Walter;C A Gross
中科院分区：
文献类型：
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作者：
David B. Straus;William Walter;C A Gross
大肠杆菌中热休克基因的表达受RNA聚合酶的另一个σ因子σ 32的作用控制，σ 32指导核心RNA聚合酶识别热休克基因的启动子。在从30摄氏度转变到42摄氏度之后，西格玛32的水平和热休克启动子处的转录起始都瞬时增加，表明热休克基因表达受西格玛32浓度变化的调节。在这里，我们报告说，热休克基因的表达是由在某些条件下的活动变化的西格玛32。我们的研究结果表明，热休克蛋白的合成，这是以下的转变从42摄氏度下降到30度，发生的结果，减少转录起始热休克启动子，但这种抑制伴随着只有一个小的下降，在西格玛32的水平。此外，热休克蛋白的诱导后，从多拷贝质粒过量生产的西格玛32只是短暂的，尽管事实上，西格玛32的水平仍然升高。组成性过量生产的西格玛32也未能导致成比例增加热休克基因转录。这三个例子表明，在过度热休克基因表达的条件下，σ 32的活性降低。
The expression of heat shock genes in Escherichia coli is controlled by the action of an alternate sigma-factor of RNA polymerase, sigma 32, which directs core RNA polymerase to recognize the promoters for heat shock genes. After a shift from 30 degrees C to 42 degrees C, both the level of sigma 32 and transcription initiation at heat shock promoters transiently increase, indicating that heat shock gene expression is regulated by changes in the concentration of sigma 32. Here, we report that heat shock gene expression is regulated by changes in the activity of sigma 32 under some conditions. Our results show that the transient repression of heat shock protein synthesis, which follows a shift down from 42 degrees C to 30 degrees, occurs as a result of decreased transcription initiation at heat shock promoters, but this repression is accompanied by only a small decrease in the level of sigma 32. In addition, the induction of heat shock proteins following overproduction of sigma 32 from a multicopy plasmid is only transient, despite the fact that the level of sigma 32 remains elevated. Constitutive overproduction of sigma 32 also fails to cause a proportionate increase in heat shock gene transcription. These three examples suggest that the activity of sigma 32 is reduced under conditions of excess heat shock gene expression.