DksA and ppGpp directly regulate transcription of the Escherichia coli flagellar cascade.
DksA and ppGpp directly regulate transcription of the Escherichia coli flagellar cascade.
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DOI：
10.1111/j.1365-2958.2009.06939.x
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发表时间：
2009-12
影响因子：
3.6
通讯作者：
Gourse RL
中科院分区：
文献类型：
--
作者：
Lemke JJ;Durfee T;Gourse RL
大肠杆菌鞭毛装置的组成部分在由主调节因子FlhDC激活的三级转录级联中合成。级联反应协调大量基因产物的合成速率，使之相互协调，并与营养条件协调。最近的全基因组研究报道，鞭毛转录在缺乏转录调节因子DksA或ppGpp的细胞中改变，但一些或所有报道的影响可能是间接的，有些是矛盾的。我们在这里报告，在所有三个水平的级联启动子的活动是高得多的菌株缺乏dksA，导致鞭毛蛋白和hyperflagellated细胞的过度生产。在体外，DksA/ppGpp抑制flhDC启动子和σ70依赖性fliA启动子转录σ28的基因。然而，DksA和ppGpp在体外不影响σ28依赖性fliA启动子或σ28依赖性fliC启动子，这表明DksA/ppGpp对FlhDC和σ28表达的直接影响间接介导了对这些基因在体内表达的显著影响。我们的结论是，DksA/ppGpp抑制鞭毛级联在稳定期和饥饿后的表达，从而协调鞭毛和核糖体组装，并防止消耗稀缺的能源资源上的两个细胞的最大的大分子复合物的合成。
The components of the Escherichia coli flagella apparatus are synthesized in a three-level transcriptional cascade activated by the master regulator FlhDC. The cascade coordinates the synthesis rates of a large number of gene products with each other and with nutritional conditions. Recent genome-wide studies have reported that flagellar transcription is altered in cells lacking the transcription regulators DksA or ppGpp, but some or all reported effects could be indirect, and some are contradictory. We report here that the activities of promoters at all three levels of the cascade are much higher in strains lacking dksA, resulting in overproduction of flagellin and hyperflagellated cells. In vitro, DksA/ppGpp inhibits the flhDC promoter and the σ70-dependent fliA promoter transcribing the gene for σ28. However, DksA and ppGpp do not affect the σ28-dependent fliA promoter or the σ28-dependent fliC promoter in vitro, suggesting that the dramatic effects on expression of those genes in vivo are mediated indirectly through direct effects of DksA/ppGpp on FlhDC and σ28 expression. We conclude that DksA/ppGpp inhibits expression of the flagellar cascade during stationary phase and following starvation, thereby coordinating flagella and ribosome assembly and preventing expenditure of scarce energy resources on synthesis of two of the cell’s largest macromolecular complexes.
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影响因子：
4.8
作者：
Liu, MZ;Durfee, T;Blattner, FR
通讯作者：
Blattner, FR
DOI：
10.1073/pnas.0705561104
发表时间：
2007-07-31
影响因子：
11.1
作者：
Bougdour, Alexandre;Gottesman, Susan
通讯作者：
Gottesman, Susan
影响因子：
3.6
作者：
Lehnen, D;Blumer, C;Unden, G
通讯作者：
Unden, G
影响因子：
3.2
作者：
Bettenbrock, Katja;Sauter, Thomas;Gilles, Ernst-Dieter
通讯作者：
Gilles, Ernst-Dieter
影响因子：
16
作者：
Murray, HD;Schneider, DA;Gourse, RL
通讯作者：
Gourse, RL