Muffler A, Traulsen D D, Lange R, Hengge-Aronis R
Department of Biology, University of Konstanz, Germany.
J Bacteriol. 1996 Mar;178(6):1607-13. doi: 10.1128/jb.178.6.1607-1613.1996.
The sigma(s) subunit of RNA polymerase (encoded by the rpoS gene) is a master regulator in a complex regulatory network that governs the expression of many stationary-phase-induced and osmotically regulated genes in Escherichia coli. rpoS expression is itself osmotically regulated by a mechanism that operates at the posttranscriptional level. Cells growing at high osmolarity already exhibit increased levels of sigma(s) during the exponential phase of growth. Osmotic induction of rpoS can be triggered by addition of NaCl or sucrose and is alleviated by glycine betaine. Stimulation of rpoS translation and a change in the half-life of sigma(s) from 3 to 50 min both contribute to osmotic induction. Experiments with lacZ fusions inserted at different positions within the rpoS gene indicate that an element required for sigma(s) degradation is encoded between nucleotides 379 and 742 of the rpoS coding sequence.
RNA聚合酶的σ（sigma）亚基（由rpoS基因编码）是一个复杂调控网络中的主要调节因子，该网络控制着大肠杆菌中许多稳定期诱导和渗透压调节基因的表达。rpoS的表达本身通过一种在转录后水平起作用的机制受到渗透压调节。在高渗透压下生长的细胞在指数生长期已经表现出σ亚基水平的增加。rpoS的渗透压诱导可以通过添加NaCl或蔗糖触发，并被甘氨酸甜菜碱缓解。rpoS翻译的刺激以及σ亚基半衰期从3分钟到50分钟的变化都有助于渗透压诱导。在rpoS基因内不同位置插入lacZ融合体的实验表明，σ亚基降解所需的一个元件编码在rpoS编码序列的第379至742个核苷酸之间。
