RpoS proteolysis is regulated by a mechanism that does not require the SprE (RssB) response regulator phosphorylation site.
RpoS proteolysis is regulated by a mechanism that does not require the SprE (RssB) response regulator phosphorylation site.
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RpoS 蛋白水解通过不需要 SprE (RssB) 反应调节器磷酸化位点的机制进行调节。
DOI：
10.1128/jb.186.21.7403-7410.2004
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
Silhavy,ThomasJ
中科院分区：
文献类型：
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作者：
Peterson,CelesteN;Ruiz,Natividad;Silhavy,ThomasJ
在大肠杆菌中，反应调节因子SprE（RssB）通过将σ因子RpoS递送至ClpXP蛋白酶来促进其降解。这一过程受到调控：RpoS在对数期降解，但在碳饥饿时变得稳定，导致其积累。由于SprE含有一个具有保守磷酸化位点（D58）的CheY结构域，流行的模型假定这种控制是由磷酸化介导的。为了测试这个模型，我们突变了sprE染色体等位基因的保守反应调节磷酸化位点（D58A），并监测了碳饥饿时的RpoS水平。虽然磷酸化有助于SprE的基础活性，我们发现，RpoS蛋白水解仍然受到碳饥饿。此外，我们的研究结果表明，野生型SprE的磷酸化发生的机制是独立的乙酰磷酸。
InEscherichia colithe response regulator SprE (RssB) facilitates degradation of the sigma factor RpoS by delivering it to the ClpXP protease. This process is regulated: RpoS is degraded in logarithmic phase but becomes stable upon carbon starvation, resulting in its accumulation. Because SprE contains a CheY domain with a conserved phosphorylation site (D58), the prevailing model posits that this control is mediated by phosphorylation. To test this model, we mutated the conserved response regulator phosphorylation site (D58A) of the chromosomal allele ofsprEand monitored RpoS levels in response to carbon starvation. Though phosphorylation contributed to the SprE basal activity, we found that RpoS proteolysis was still regulated upon carbon starvation. Furthermore, our results indicate that phosphorylation of wild-type SprE occurs by a mechanism that is independent of acetyl phosphate.