REGULATION OF THE PROMOTERS AND TRANSCRIPTS OF RPOH, THE ESCHERICHIA-COLI HEAT-SHOCK REGULATORY GENE
REGULATION OF THE PROMOTERS AND TRANSCRIPTS OF RPOH, THE ESCHERICHIA-COLI HEAT-SHOCK REGULATORY GENE
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DOI：
10.1101/gad.1.5.419
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发表时间：
1987-07-01
影响因子：
10.5
通讯作者：
GROSS, CA
中科院分区：
文献类型：
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作者：
ERICKSON, JW;VAUGHN, V;GROSS, CA
在大肠杆菌中，rpoH（htpR）基因的产物sigma 32指导RNA聚合酶在所有温度下从热休克启动子开始转录。当细胞暴露于高温时，由于sigma 32-RNA聚合酶的转录起始增加，热休克基因的转录增加。作为了解热休克反应调控的一步，我们已经研究了rpoH基因的转录。使用S1定位，启动子克隆，并在体外转录，我们已经确定了rpoH转录单位的启动子和终止子。rpoH转录物是单顺反子的，并且源自至少三个启动子。没有启动子被sigma 32-RNA聚合酶识别。其中两种被sigma 70-RNA聚合酶识别，在低温和高温下都有活性。我们不知道哪种形式的RNA聚合酶识别第三个启动子。来自该启动子的转录物仅在高温下是丰富的，并且在转变到50 ° C的致死温度后存在，甚至在没有来自其他rpoH启动子的可检测的转录物的时候。在从30 ° C转变到43.5 ° C后8分钟，rpoH mRNA的量增加了5倍，但rpoH mRNA的合成增加了不到2倍，这表明存在rpoH mRNA水平的转录后控制，并且可能是sigma 32。
In Escherichia coli the product of the rpoH (htpR) gene, sigma 32, directs RNA polymerase to initiate transcription from heat shock promoters at all temperatures. Transcription of the heat shock genes is increased when cells are exposed to high temperatures because of increased transcription initiation by sigma 32-RNA polymerase. As a step toward understanding the regulation of the heat shock response we have examined the transcription of the rpoH gene. Using S1 mapping, promoter cloning, and in vitro transcription, we have identified the promoters and the terminator for the rpoH transcription unit. The rpoH transcripts are monocistronic and originate from at least three promoters. None of the promoters is recognized by sigma 32-RNA polymerase. Two are recognized by sigma 70-RNA polymerase and are active at both low and high growth temperatures. We do not know what form of RNA polymerase recognizes the third promoter. Transcripts from this promoter are abundant only at high temperature and are present after shift to the lethal temperature of 50 degrees C, even at times when there are no detectable transcripts from the other rpoH promoters. The amount of rpoH mRNA increases fivefold by 8 min after shift from 30 to 43.5 degrees C but rpoH mRNA synthesis increases by less than twofold, indicating that there is post-transcriptional control of the level of rpoH mRNA and presumably of sigma 32.