THE ACTIVITY OF SIGMA(E), AN ESCHERICHIA-COLI HEAT-INDUCIBLE SIGMA-FACTOR, IS MODULATED BY EXPRESSION OF OUTER-MEMBRANE PROTEINS
THE ACTIVITY OF SIGMA(E), AN ESCHERICHIA-COLI HEAT-INDUCIBLE SIGMA-FACTOR, IS MODULATED BY EXPRESSION OF OUTER-MEMBRANE PROTEINS
复制标题
DOI：
10.1101/gad.7.12b.2618
复制
发表时间：
1993-12-01
影响因子：
10.5
通讯作者：
GROSS, CA
中科院分区：
文献类型：
--
作者：
MECSAS, J;ROUVIERE, PE;GROSS, CA
在大肠杆菌中，西格玛(E)和西格玛32是两种热和乙醇诱导的西格玛因子。Sigma32调节子也是由细胞质中未折叠和错误折叠的蛋白质诱导的，并且Sigma32调节子中的许多蛋白质的功能是与细胞质蛋白结合并帮助它们折叠或去折叠。为了进一步了解sigma(E)调节子的功能，我们寻找了影响sigma(E)活性的突变体。我们的结果表明，外膜蛋白的表达产生的信号调节Sigma(E)的活性。具体地说，Sigma(E)活性是由OMPS表达增加诱导的，而OMPS表达减少则降低。此外，导致OMP错误折叠的突变会诱导Sigma(E)活性。这一信号是在OMP和周质蛋白在分泌途径中发散后产生的，而不是OMP前体在细胞质中积累的结果。我们的结果表明，OMPS的这种效应是Sigma(E)调节子所特有的，因为上述突变都没有影响Sigma(32)的活性。我们认为，sigma(E)调节子参与了发生在胞质外室的过程，这两个热诱导调节子可能在监测细胞质(Sigma32)和外膜(sigma(E))的蛋白质状态方面具有不同但互补的作用。
Sigma(E) and sigma32 are two heat- and ethanol-inducible sigma-factors in Escherichia coli. The sigma32 regulon is also induced by unfolded and misfolded proteins in the cytoplasm, and the function of many of the proteins in the sigma32 regulon is to bind to cytoplasmic proteins and assist them in folding or unfolding. To further understand the function of the sigma(E) regulon, we searched for mutants that affected sigma(E) activity. Our results indicate that a signal generated by expression of outer membrane proteins modulates sigma(E) activity. Specifically, sigma(E) activity is induced by increased expression of OMPs and is reduced by decreased expression of OMPs. In addition, mutations that cause misfolded OMPs induce sigma(E) activity. This signal is generated after the fate of OMPs and periplasmic proteins diverge in the secretory pathway and is not the result of an accumulation of OMP precursors in the cytoplasm. Our results indicate that this effect of OMPs is specific to the sigma(E) regulon, because none of the above mutations affect sigma(32) activity. We propose that the sigma(E) regulon is involved in processes that occur in extracytoplasmic compartments and that these two heat-inducible regulons may have distinct but complementary roles of monitoring the state of proteins in the cytoplasm (sigma32) and outer membrane (sigma(E)).