Role of Escherichia coli cspA promoter sequences and adaptation of translational apparatus in the cold shock response
Role of Escherichia coli cspA promoter sequences and adaptation of translational apparatus in the cold shock response
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DOI：
10.1007/s004380050571
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发表时间：
1997-10-01
期刊：
影响因子：
--
通讯作者：
Gualerzi, CO
中科院分区：
文献类型：
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作者：
Goldenberg, D;Azar, I;Gualerzi, CO
当生长温度从37摄氏度上升到15摄氏度时，大肠杆菌的主要冷休克蛋白CspA的水平急剧上升。为了研究这种诱导的分子基础，我们通过分析携带一组与lacZ或cat基因融合的可变长度cspA启动子片段的细胞中转录物的稳态水平和报告基因的表达，考虑了转录和转录后控制的相关性。我们证明：(i)核心cspA启动子（从-40到+16）对冷休克有响应，在-36的突变使启动子在低温下的相对活性增加了三倍；（ii） -40上游序列对37℃下的表达有正向影响，但对冷休克响应没有影响；（iii）由于其对mRNA稳定性的影响，下游序列（从+81到+165）在37℃下降低表达并增加冷休克反应的强度；（iv） GCACATCA和CCAAT基序的突变，分别存在于+1/-4和-10和-35元件之间，不影响cspA启动子的冷休克反应；(v)冷休克后，蛋白质合成机制发生修饰，使cspA mRNA相对于非冷休克cat和lacZ mRNA优先翻译。cspA核心启动子在冷休克后所显示的数量适度的转录激活表明，转录激活只有在与转录后控制（如mRNA稳定性和翻译装置的改变）耦合时才能显著促进冷休克诱导。
A shift in growth temperature from 37 degrees C to 15 degrees C leads to a dramatic increase in the level of CspA, the major cold shock protein of Escherichia coli. To investigate the molecular basis of this induction, we considered the relevance of transcriptional and posttranscriptional controls by analyzing the steady-state levels of transcripts and the expression of reporter genes in cells carrying a set of cspA promoter fragments of variable length fused to lacZ or cat genes. We demonstrate that: (i) the core cspA promoter (from -40 to +16) responds to cold shock and a mutation at -36 increases the relative activity of the promoter at low temperature by threefold; (ii) the sequences upstream of -40 have a positive effect on expression at 37 degrees C, but no effect on the cold shock response; (iii) by virtue of their influence on mRNA stability, the downstream sequences (from +81 to +165) reduce expression at 37 degrees C and increase the intensity of the cold shock response; (iv) mutations in the GCACATCA and CCAAT motifs, present at +1/-4 and between the -10 and -35 elements, respectively, do not affect the cold shock response of the cspA promoter; (v) following cold shock, a modification of the protein synthetic machinery takes place that allows preferential translation of cspA mRNA relative to the non-cold shock cat and lacZ mRNAs. The quantitatively modest transcriptional activation shown by the core promoter of cspA following cold shock suggests that transcriptional activation can significantly contribute to cold shock induction only when coupled to posttranscriptional controls, such as alterations in mRNA stability and of the translational apparatus.