Department of Molecular Microbiology and Biotechnology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
Department of Molecular Microbiology and Biotechnology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel; MIGAL, Galilee Research Center, Kiriat Shmone, Israel.
J Mol Biol. 2014 Jan 23;426(2):460-6. doi: 10.1016/j.jmb.2013.10.018. Epub 2013 Oct 19.
The heat shock response is one of the main global regulatory networks in all organisms and involves an increased cellular level of chaperones and proteases to enable correct protein folding and balanced growth. One of the major heat shock chaperones in Escherichia coli is GroESL, composed of GroES and GroEL (the bacterial Hsp10 and Hsp60 homologues), which is essential for refolding of misfolded proteins. GroESL was previously shown to play a role in the regulation of the heat shock response by promoting the proteolysis of the regulatory protein--sigma32 (RpoH), the heat shock transcription activator. Here we show the involvement of GroESL in another proteolytic process, this of the major RNA chaperone--CspC--that specifically stabilizes the transcripts of several stress-related genes. Evidence is provided for an interaction between GroESL and CspC that results in enhanced, temperature-dependent proteolysis of the latter. This interaction is of regulatory importance, as reduction in the cellular levels of CspC leads to a decrease in stability of the major heat shock gene transcripts.
热休克反应是所有生物体中主要的全局调控网络之一，它涉及到细胞内伴侣蛋白和蛋白酶水平的升高，以实现蛋白质的正确折叠和平衡生长。在大肠杆菌中，主要的热休克伴侣蛋白之一是 GroESL，它由 GroES 和 GroEL（细菌的 Hsp10 和 Hsp60 同源物）组成，对于错误折叠蛋白的重折叠至关重要。先前的研究表明，GroESL 通过促进调节蛋白——sigma32（RpoH）的蛋白酶解来发挥作用，sigma32 是热休克转录激活因子。在这里，我们展示了 GroESL 参与另一种蛋白水解过程，即主要 RNA 伴侣蛋白——CspC 的蛋白水解过程，CspC 特异性稳定几种与应激相关基因的转录本。有证据表明 GroESL 与 CspC 之间存在相互作用，导致后者的温度依赖性蛋白水解增强。这种相互作用具有重要的调节意义，因为细胞内 CspC 水平的降低会导致主要热休克基因转录本的稳定性降低。
