Regulation of or factor competition by the alarmone ppGpp
Regulation of or factor competition by the alarmone ppGpp
复制标题
DOI：
10.1101/gad.227902
复制
发表时间：
2002-05-15
影响因子：
10.5
通讯作者：
Nyström, T
中科院分区：
文献类型：
--
作者：
Jishage, M;Kvint, K;Nyström, T
许多由替代因子控制的调节子，包括sigma（S）和sigma（32），在缺乏报警素ppGpp的细胞中诱导较差。我们表明ppGpp对于sigma（S）依赖性启动子的活性不是绝对必需的，因为sigma（70）的产生不足、rpoD中的特定突变（rpoD 40和rpoD 35）或Rsd（反sigma（70））的过度产生在没有ppGpp积累的情况下恢复了体内sigma（S）依赖性启动子的表达。用重组RNA聚合酶进行的体外转录/竞争测定显示，ppGpp的添加降低了野生型sigma（70）与sigma（32）竞争核心结合的能力，并且由rpoD 40和rpoD 35编码的突变体或70蛋白质的竞争效率低于野生型sigma（70）。类似地，体内竞争测定显示，在缺乏ppGpp的细胞中，sigma（32）和us与sigma（70）竞争的能力都降低。一致地，在ppGpp缺陷细胞中，与核心结合的sigma（S）和sigma（32）的分数显著降低。因此，严格的反应包括一种机制，改变相对竞争力的σ因子在生理应激期间根据细胞的需求。
Many regulons controlled by alternative or factors, including sigma(S) and sigma(32), are poorly induced in cells lacking the alarmone ppGpp. We show that ppGpp is not absolutely required for the activity of sigma(S)-dependent promoters because underproduction of sigma(70), specific mutations in rpoD (rpoD40 and rpoD35), or overproduction of Rsd (anti-sigma(70)) restored expression from sigma(S)-dependent promoters in vivo in the absence of ppGpp accumulation. An in vitro transcription/competition assay with reconstituted RNA polymerase showed that addition of ppGpp reduces the ability of wild-type sigma(70) to compete with sigma(32) for core binding and the mutant or 70 proteins, encoded by rpoD40 and rpoD35, compete less efficiently than wild-type sigma(70). Similarly, an in vivo competition assay showed that the ability of both sigma(32) and us to compete with sigma(70) is diminished in cells lacking ppGpp. Consistently, the fraction of sigma(S) and sigma(32) bound to core was drastically reduced in ppGpp-deficient cells. Thus, the stringent response encompasses a mechanism that alters the relative competitiveness of sigma factors in accordance with cellular demands during physiological stress.