DksA represses ribosomal gene transcription in Pseudomonas aeruginosa by interacting with RNA polymerase on ribosomal promoters
DksA represses ribosomal gene transcription in Pseudomonas aeruginosa by interacting with RNA polymerase on ribosomal promoters
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DOI：
10.1111/j.1365-2958.2005.04597.x
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发表时间：
2005-05-01
影响因子：
3.6
通讯作者：
van Delden, C
中科院分区：
文献类型：
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作者：
Perron, K;Comte, R;van Delden, C
在大肠杆菌中，核糖体RNA（rRNA）的转录受H-NS和Fis蛋白以及小信号分子ppGpp和起始核苷酸的调节。在氨基酸饥饿期间，ppGpp的浓度增加，并且这种警报素与RNA聚合酶（RNAP）的结合导致rRNA转录的抑制，这是称为严格反应的调节事件。在这里，我们表明，在铜绿假单胞菌DksA，多效性的蛋白质，是一个负调控rRNA转录在指数增长和严格的条件。dksA突变体过表达rRNA，而不影响ppGpp的产生。细胞分级分离和染色体免疫沉淀实验表明，DksA与DNA，特别是与核糖体基因的启动子在体内。与rRNA启动子的结合在严格响应期间特异性增加，并且与RNAP与这些区域的结合相关。此外，DksA可以与RNAP亚基在体内共纯化。DNA带移实验表明，DksA，协同ppGpp，增加RNAP的核糖体启动子的结合。因此，DksA可能是铜绿假单胞菌rRNA基因转录的一个新的调控因子。
In Escherichia coli transcription of ribosomal RNA (rRNA) is regulated by the H-NS and Fis proteins, as well as by the small signal molecule ppGpp and the initiating nucleotides. During amino acid starvation, the concentration of ppGpp increases, and binding of this alarmone to RNA polymerase (RNAP) leads to inhibition of rRNA transcription, a regulatory event called stringent response. Here we show that in Pseudomonas aeruginosa DksA, a protein with pleiotropic effects, is a negative regulator of rRNA transcription both during exponential growth and stringent conditions. A dksA mutant overexpresses rRNA, without being affected in the production of ppGpp. Cell-fractionation and chromosome immuno-precipitation experiments demonstrate that DksA is associated with DNA, in particular with promoters of ribosomal genes in vivo. The binding to rRNA promoters specifically increases during stringent response, and correlates with the binding of RNAP to these regions. Moreover DksA can be copurified with RNAP subunits in vivo. DNA band shift experiments show that DksA, in synergy with ppGpp, increases the binding of RNAP to ribosomal promoters. Therefore DksA might be a new regulator of rRNA transcription in P. aeruginosa.