A chaperone network controls the heat shock response in E-coli
A chaperone network controls the heat shock response in E-coli
复制标题
DOI：
10.1101/gad.1219204
复制
发表时间：
2004-11-15
影响因子：
10.5
通讯作者：
Gross, CA
中科院分区：
文献类型：
--
作者：
Guisbert, E;Herman, C;Gross, CA
热休克反应控制分子伴侣和蛋白酶的水平，以确保蛋白质折叠的适当细胞环境。在大肠杆菌中，这种反应由细菌特异性转录因子 sigma(32) 介导。 DnaK 伴侣机器调节 sigma(32) 的数量和活性，从而将 sigma(32) 功能与细胞蛋白质折叠状态耦合。在这篇手稿中，我们分析了大肠杆菌中其他主要伴侣调节 sigma(32) 的能力，并证明 GroEL/S 伴侣蛋白是 sigma(32) 的附加调节剂。我们表明，增加 GroEL/S 水平会导致体内 sigma(32) 活性降低，并且可以通过 GroEL/S 特异性底物的共过表达来消除这种影响。我们还表明，体内 GroEL/S 的消耗通过增加 sigma(32) 水平导致 sigma(32) 上调。此外，我们还发现，在应激条件下改变 GroEL/S 水平会导致热激反应发生可测量的变化。使用纯化的蛋白质，我们表明 GroEL 与 sigma(32) 结合并在体外减少 sigma(32) 依赖性转录，表明这种调节是直接的。我们讨论了为什么使用伴侣网络来调节 sigma(32) 可以更灵敏、更准确地检测蛋白质折叠环境。
The heat shock response controls levels of chaperones and proteases to ensure a proper cellular environment for protein folding. In Escherichia coli, this response is mediated by the bacterial-specific transcription factor, sigma(32). The DnaK chaperone machine regulates both the amount and activity of sigma(32), thereby coupling sigma(32) function to the cellular protein folding state. In this manuscript, we analyze the ability of other major chaperones in E. coli to regulate sigma(32), and we demonstrate that the GroEL/S chaperonin is an additional regulator of sigma(32). We show that increasing the level of GroEL/S leads to a decrease in sigma(32) activity in vivo and this effect can be eliminated by co-overexpression of a GroEL/S-specific substrate. We also show that depletion of GroEL/S in vivo leads to up-regulation of sigma(32) by increasing the level of sigma(32). In addition, we show that changing the levels of GroEL/S during stress conditions leads to measurable changes in the heat shock response. Using purified proteins, we show that that GroEL binds to sigma(32) and decreases sigma(32)-dependent transcription in vitro, suggesting that this regulation is direct. We discuss why using a chaperone network to regulate sigma(32) results in a more sensitive and accurate detection of the protein folding environment.