Heterologous expression of a plant RelA-SpoT homologue results in increased stress tolerance in Saccharomyces cerevisiae by accumulation of the bacterial alarmone ppGpp
Heterologous expression of a plant RelA-SpoT homologue results in increased stress tolerance in Saccharomyces cerevisiae by accumulation of the bacterial alarmone ppGpp
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植物 RelA-SpoT 同源物的异源表达通过细菌警报素 ppGpp 的积累提高了酿酒酵母的胁迫耐受性
DOI：
10.1099/mic.0.057638-0
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发表时间：
2012
期刊：
影响因子：
1.5
通讯作者：
Ozeki Y
中科院分区：
文献类型：
--
作者：
Ochi K;Nishizawa T;Inaoka T;Yamada A;Hashimoto K;Hosaka T;Okamoto S;Ozeki Y
细菌警报蛋白ppGpp只存在于细菌和植物的叶绿体中，而不存在于哺乳动物细胞或真核微生物(如酵母和真菌)中。因此，ppGpp信号系统在真核生物中的重要性在很大程度上被忽视了。在这里，我们证明了从嗜盐植物Suaeda Japan中分离的arelA-SPOTOLOGUE(Sj-RSH)在酵母中的异源表达导致ppGpp的积累，同时伴随着对各种胁迫刺激的耐受性的增强，如渗透胁迫、乙醇、过氧化氢、高温和冷冻。与细菌ppGpp积累不同，ppGpp在生长前期积累，而在生长后期不积累。此外，营养减速导致ppGpp水平下降，表明观察到的合成ppGpp的Sj-RSH活性不是饥饿依赖的，与我们基于细菌的预期相反。积累的ppGpp仅存在于胞质部分，而不存在于线粒体部分，这可能反映了核糖体非依赖的ppGpp合成INS。酿酒厂。与细菌肌苷脱氢酶(IMP)不同，IMP脱氢酶OFS。酿酒人对ppGpp不敏感。基因芯片分析表明，ppGpp的积累引起了基因表达的显著变化，包括上调和下调，包括线粒体基因表达的变化。在未知功能的假想基因YBR072C-A中检测到最显著的上调(38倍)，其次是许多其他已知的应激反应基因。酿酒酵母可能为揭示和分析真核细胞中的ppGpp信号系统提供新的机会。
The bacterial alarmone ppGpp is present only in bacteria and the chloroplasts of plants, but not in mammalian cells or eukaryotic micro-organisms such as yeasts and fungi. The importance of the ppGpp signalling system in eukaryotes has therefore been largely overlooked. Here, we demonstrated that heterologous expression of arelA-spoThomologue (Sj-RSH) isolated from the halophilic plantSuaeda japonicain the yeastSaccharomyces cerevisiaeresults in accumulation of ppGpp, accompanied by enhancement of tolerance against various stress stimuli, such as osmotic stress, ethanol, hydrogen peroxide, high temperature and freezing. Unlike bacterial ppGpp accumulation, ppGpp was accumulated in the early growth phase but not in the late growth phase. Moreover, nutritional downshift resulted in a decrease in ppGpp level, suggesting that the observed Sj-RSH activity to synthesize ppGpp is not starvation-dependent, contrary to our expectations based on bacteria. Accumulated ppGpp was found to be present solely in the cytosolic fraction and not in the mitochondrial fraction, perhaps reflecting the ribosome-independent ppGpp synthesis inS. cerevisiaecells. Unlike bacterial inosine monophosphate (IMP) dehydrogenases, the IMP dehydrogenase ofS. cerevisiaewas insensitive to ppGpp. Microarray analysis showed that ppGpp accumulation gave rise to marked changes in gene expression, with both upregulation and downregulation, including changes in mitochondrial gene expression. The most prominent upregulation (38-fold) was detected in the hypothetical gene YBR072C–A of unknown function, followed by many other known stress-responsive genes.S. cerevisiaemay provide new opportunities to uncover and analyse the ppGpp signalling system in eukaryotic cells.