Trehalose synthesis is induced upon exposure of Escherichia coli to cold and is essential for viability at low temperatures
Trehalose synthesis is induced upon exposure of Escherichia coli to cold and is essential for viability at low temperatures
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DOI：
10.1073/pnas.142314099
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发表时间：
2002-07-23
影响因子：
11.1
通讯作者：
Goldberg, AL
中科院分区：
文献类型：
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作者：
Kandror, O;DeLeon, A;Goldberg, AL
海藻糖在热休克和渗透胁迫期间在微生物中显著积累，并有助于保护细胞免受热损伤和氧自由基的侵害。在这里，我们证明了这种糖在细菌的冷适应中的重要作用。一种不能产生海藻糖的突变大肠杆菌菌株在40 ℃下比野生型死亡快得多。用负责海藻糖合成的otsA/otsB基因转化突变体，在4 ℃下恢复了海藻糖含量和细胞活力。在温度从37 ℃降至16 ℃（“冷休克”）后，野生型细胞中的海藻糖水平增加了8倍。虽然这种海藻糖的积累并不影响生长在WC，它增强了细胞活力时，温度进一步下降到4degreesC。在海藻糖积累之前，编码OtsA/OtsB的mRNA水平显著增加。这种诱导需要或因子RpoS，但独立于主要的冷休克蛋白CspA。otsA/B mRNA在16 ℃时比在37 ℃时稳定得多，并含有冷诱导mRNA的“下游盒”特征。因此，otsA/otsB诱导和海藻糖合成在冷休克（以及在热休克）期间被激活，并且在E.大肠杆菌（可能还有其他生物）对低温的耐受性。
Trehalose accumulates dramatically in microorganisms during heat shock and osmotic stress and helps protect cells against thermal injury and oxygen radicals. Here we demonstrate an important role of this sugar in cold-adaptation of bacteria. A mutant Escherichia coli strain unable to produce trehalose died much faster than the wild type at 4degreesC. Transformation of the mutant with the otsA/otsB genes, responsible for trehalose synthesis, restored trehalose content and cell viability at 4degreesC. After temperature downshift from 37degreesC to 16degreesC ("cold shock"), trehalose levels in wild-type cells increased up to 8-fold. Although this accumulation of trehalose did not influence growth at WC, it enhanced cell viability when the temperature fell further to 4degreesC. Before the trehalose build-up, levels of mRNA encoding OtsA/OtsB increased markedly. This induction required the or factor, RpoS, but was independent of the major cold-shock protein, CspA. otsA/B mRNA was much more stable at 16degreesC than at 37degreesC and contained a "downstream box" characteristic of cold-inducible mRNAs. Thus, otsA/otsB induction and trehalose synthesis are activated during cold shock (as well as during heat shock) and play an important role in resistance of E. coli (and probably other organisms) to low temperatures.