Increased motility of Escherichia coli by insertion sequence element integration into the regulatory region of the flhD operon
Increased motility of Escherichia coli by insertion sequence element integration into the regulatory region of the flhD operon
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DOI：
10.1128/jb.186.22.7529-7537.2004
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发表时间：
2004-11-01
影响因子：
3.2
通讯作者：
Matsumura, P
中科院分区：
文献类型：
--
作者：
Barker, CS;Prüss, BM;Matsumura, P
flhD操纵子是鞭毛调节子的主操纵子，并且是代谢的全局调节器。大肠杆菌K-12菌株MG 1655的基因组序列在flhD启动子的调节区中含有IS 1插入序列元件。MG 1655的另一种储备液从E.大肠杆菌遗传储备中心。该原种含有运动性差并且在flhD启动子上游没有IS 1元件的分离物。从这些分离株中，运动亚群在运动琼脂中延长孵育后进行鉴定。纯化的能动衍生物含有一个IS 5元件插入上游的flhD启动子，和蜂群率比原来的分离株高7倍。对于能动的衍生物，flhD转录物的水平增加了2.7倍，导致fli 4转录物增加了32倍，启动子探针载体的flhB：：luxCDABE表达增加了65倍。对常用实验室菌株的集合进行IS元件插入和运动性筛选。5个菌株（RP 437、YK 410、MC 1000、W3110和W2637）在flhD启动子上游的两个位置之一处含有IS 5元件。这与高群体率有关。其他四个菌株（W1485、FB 8、MM 294和RB 791）在flhD调节区中不含IS元件，并且运动性差。引物延伸确定flhD的转录起始位点未被IS元件插入改变。我们认为，IS元件插入可能会激活转录的flhD操纵子通过减少转录抑制。
The flhD operon is the master operon of the flagellar regulon and a global regulator of metabolism. The genome sequence of the Escherichia coli K-12 strain MG1655 contained an IS1 insertion sequence element in the regulatory region of the flhD promoter. Another stock of MG1655 was obtained from the E. coli Genetic Stock Center. This stock contained isolates which were poorly motile and had no IS1 element upstream of the flhD promoter. From these isolates, motile subpopulations were identified after extended incubation in motility agar. Purified motile derivatives contained an IS5 element insertion upstream of the flhD promoter, and swarm rates were sevenfold higher than that of the original isolate. For a motile derivative, levels of flhD transcript had increased 2.7-fold, leading to a 32-fold increase in fli4 transcript and a 65-fold increase in flhB::luxCDABE expression from a promoter probe vector. A collection of commonly used lab strains was screened for IS element insertion and motility. Five strains (RP437, YK410, MC1000, W3110, and W2637) contained IS5 elements upstream of the flhD promoter at either of two locations. This correlated with high swarm rates. Four other strains (W1485, FB8, MM294, and RB791) did not contain IS elements in the flhD regulatory region and were poorly motile. Primer extension determined that the transcriptional start site of flhD was unaltered by the IS element insertions. We suggest that IS element insertion may activate transcription of the flhD operon by reducing transcriptional repression.