Growth-phase-dependent expression of the osmotically inducible gene osmC of Escherichia coli K-12
Growth-phase-dependent expression of the osmotically inducible gene osmC of Escherichia coli K-12
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DOI：
10.1046/j.1365-2958.1996.418945.x
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发表时间：
1996-02-01
影响因子：
3.6
通讯作者：
Gutierrez, C
中科院分区：
文献类型：
--
作者：
Gordia, S;Gutierrez, C
大肠杆菌渗透诱导基因 osmC 的转录由两个重叠的启动子 osmC(p1) 和 osmC(p2) 启动。通过定点诱变证实了这两个启动子的存在，osmC转录受生长期调控。在低渗透压的培养基中，osmC 的表达在减速期开始时被诱导，并在稳定期开始时持续。在渗透压升高的情况下，诱导在生长过程中发生得稍早。两个启动子在指数早期都受到抑制。 osmC(p2) 在进入稳定期期间被诱导。 osmC(p1) 的转录比丰富培养基中 osmC(p2) 的转录低约 10 倍，在对数中期开始，在稳定期早期停止。在缺乏 sigma(S)（由 rpoS 编码的稳定相 sigma 因子）的情况下，osmC(p2) 表达大大降低，而 osmC(p1) 表达不受影响。因此，osmC 作为生长函数的调节至少部分独立于 sigma(S)。
The transcription of the osmotically inducible gene osmC of Escherichia coli is initiated by two overlapping promoters, osmC(p1) and osmC(p2). The existence of these two promoters was confirmed by site-directed mutagenesis, osmC transcription is regulated by the growth phase. In a medium of low osmotic pressure, expression of osmC is induced at the onset of decelerating phase and continues during the beginning of stationary phase. At elevated osmotic pressure, the induction occurs somewhat earlier during growth. Both promoters are repressed during early exponential phase. osmC(p2) is induced during entry into stationary phase. Transcription from osmC(p1), which is approximately 10-fold lower than that of osmC(p2) in rich medium, starts during the mid-log phase and stops in early stationary phase. In the absence of sigma(S), the stationary-phase sigma factor encoded by rpoS, osmC(p2) expression is much reduced while expression of osmC(p1) is unaffected. As a consequence, the regulation of osmC as a function of growth is at least partially independent of sigma(S).