Expression of the groESL operon is cell-cycle controlled in Caulobacter crescentus
Expression of the groESL operon is cell-cycle controlled in Caulobacter crescentus
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DOI：
10.1046/j.1365-2958.1996.347879.x
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发表时间：
1996-01-01
影响因子：
3.6
通讯作者：
Gomes, SL
中科院分区：
文献类型：
--
作者：
Avedissian, M;Gomes, SL
对新月柄杆菌groESL操纵子进行克隆、测序，发现其与先前描述的groES和groEL基因和蛋白质同源。结果表明，C.新月体以双顺反子操纵子组织。groESL mRNA的热休克诱导不是瞬时的，在40 ℃下2小时后可以观察到高水平的转录物。引物延伸实验表明转录起始于两个位点。在热休克过程中，只有靠近groES编码区的起始位点被高度诱导。对应于热休克诱导转录物的启动子具有与大肠杆菌sigma（32）启动子非常相似的-10和-35区。在正常温度下，groESL操纵子的转录受细胞周期控制，并且两种转录物在分裂前细胞中协同增加。与lacZ报告基因的转录融合和groESL操纵子的启动子区域内的缺失表明，没有序列的热休克启动子的上游是必要的时间控制。在热休克启动子和groES翻译起始位点之间存在一个11 bp的反向重复序列，与其他细菌的热休克基因前的反向重复序列非常相似，可能在C. crescentus groESL表达。
The Caulobacter crescentus groESL operon was cloned, sequenced and found to be homologous to previously described groES and groEL genes and proteins. The size of the groESL-specific transcript (2.3 kb) suggested that groES and groEL of C. crescentus are organized in a bicistronic operon. Heat-shock induction of groESL mRNA is not transient, high levels of the transcript can be observed after 2 h at 40 degrees C. Primer extension experiments showed that transcription initiated at two sites. Only the start site closer to the groES coding region was highly induced during heat shock. The promoter corresponding to the heatshock-inducible transcript has -10 and -35 regions very similar to Escherichia coli sigma(32) promoters. At normal temperatures, transcription of the groESL operon is cell-cycle controlled and both transcripts increase co-ordinately in pre-divisional cells. Transcription fusions with a lacZ reporter gene and deletions within the promoter region of the groESL operon have shown that no sequences upstream of the heat-shock promoter are necessary for temporal control. An 11 bp inverted repeat, located between the heat-shock promoter and the translation start site of groES and very similar to inverted repeats found in front of several heat-shock genes of other bacteria, may play a role in cell-cycle control of C. crescentus groESL expression.