Hücker Sarah Maria, Simon Svenja, Scherer Siegfried, Neuhaus Klaus
Chair for Microbial Ecology, Technische Universität München, Weihenstephaner Berg 3, 85354 Freising, Germany.
Chair for Data Analysis and Visualization, Department of Computer and Information Science, University of Konstanz, Box 78, 78457 Konstanz, Germany.
FEMS Microbiol Lett. 2017 Jan;364(2). doi: 10.1093/femsle/fnw262. Epub 2016 Nov 16.
The enteric pathogen Escherichia coli O157:H7 Sakai (EHEC) is able to grow at lower temperatures compared to commensal E. coli Growth at environmental conditions displays complex challenges different to those in a host. EHEC was grown at 37°C and at 14°C with 4% NaCl, a combination of cold and osmotic stress as present in the food chain. Comparison of RNAseq and RIBOseq data provided a snap shot of ongoing transcription and translation, differentiating transcriptional and post-transcriptional gene regulation, respectively. Indeed, cold and osmotic stress related genes are simultaneously regulated at both levels, but translational regulation clearly dominates. Special emphasis was given to genes regulated by RNA secondary structures in their 5UTRs, such as RNA thermometers and riboswitches, or genes controlled by small RNAs encoded in trans The results reveal large differences in gene expression between short-time shock compared to adaptation in combined cold and osmotic stress. Whereas the majority of cold shock proteins, such as CspA, are translationally downregulated after adaptation, many osmotic stress genes are still significantly upregulated mainly translationally, but several also transcriptionally.
肠道病原体大肠杆菌O157:H7阪崎株（EHEC）与共生大肠杆菌相比，能够在更低的温度下生长。在环境条件下生长面临着与宿主环境不同的复杂挑战。EHEC在37°C和14°C以及4%氯化钠的条件下培养，这是食物链中存在的冷应激和渗透应激的组合。RNAseq和RIBOseq数据的比较分别提供了正在进行的转录和翻译的快照，区分了转录水平和转录后基因调控。事实上，与冷应激和渗透应激相关的基因在这两个水平上同时受到调控，但翻译调控明显占主导。特别强调了在其5'UTR中受RNA二级结构调控的基因，如RNA温度计和核糖开关，或由反式编码的小RNA控制的基因。结果显示，与在冷应激和渗透应激联合条件下的适应相比，短期应激下的基因表达存在很大差异。虽然大多数冷休克蛋白，如CspA，在适应后翻译水平下调，但许多渗透应激基因仍然显著上调，主要是翻译水平上调，但也有一些是转录水平上调。
