Fujita N, Ishihama A
Department of Molecular Genetics, National Institute of Genetics, Shizuoka, Japan.
Mol Gen Genet. 1987 Nov;210(1):10-5. doi: 10.1007/BF00337752.
Transcriptional start sites of the rpoH gene which codes for a minor sigma factor (sigma 32) of Escherichia coli RNA polymerase were determined. The rpoH gene is transcribed, both in vivo and in vitro, from two major (P1 and P2) and one minor (P2*) promoters. In vitro synthesis of the rpoH mRNAs is dependent on the major species of RNA polymerase holoenzyme (E sigma 70) but not on the minor one (E sigma 32). S1 nuclease analysis of the in vivo RNA showed that the level of rpoH transcript from the downstream P2 promoter increases rapidly when E. coli cells are transferred from 30 degrees C to 42 degrees C, while the transcript from the upstream P1 promoter remains at a constant level. Under these conditions, the metabolic stabilities of rpoH mRNAs are virtually unaffected, suggesting that the synthesis of rpoH mRNA from the P2 promoter is specifically enhanced upon heat-shock.
确定了编码大肠杆菌RNA聚合酶一种次要σ因子（σ32）的rpoH基因的转录起始位点。rpoH基因在体内和体外均从两个主要启动子（P1和P2）和一个次要启动子（P2*）转录。rpoH mRNA的体外合成依赖于RNA聚合酶全酶的主要种类（Eσ70），而不依赖于次要种类（Eσ32）。对体内RNA的S1核酸酶分析表明，当大肠杆菌细胞从30℃转移到42℃时，来自下游P2启动子的rpoH转录物水平迅速增加，而来自上游P1启动子的转录物水平保持恒定。在这些条件下，rpoH mRNA的代谢稳定性几乎不受影响，这表明热休克时从P2启动子合成rpoH mRNA会特异性增强。
