Two novel flagellar components and H-NS are involved in the motor function of Escherichia coli
Two novel flagellar components and H-NS are involved in the motor function of Escherichia coli
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DOI：
10.1006/jmbi.2000.4147
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发表时间：
2000-10-27
影响因子：
5.6
通讯作者：
Park, C
中科院分区：
文献类型：
--
作者：
Ko, M;Park, C
H - NS的一个突变导致大肠杆菌因flhDC主操纵子表达降低而无鞭毛。我们发现hns阴性菌株在有flhDC存在时恢复了其鞭毛形成，尽管所得菌株仍然不能运动。由于Δhns菌株中运动组件MotA、MotB和FliG的细胞内水平未改变，不能运动这一现象表明H - NS既影响鞭毛的生物发生，也影响其功能。我们获得了ycgR的一个插入片段，ycgR是一个假定基因，编码一个含244个氨基酸残基的蛋白质，它可抑制hns缺陷细胞的运动缺陷。通过计算机辅助运动分析评估，ycgR的插入使hns突变细胞异常低的游动速度完全恢复。用多拷贝表达yhjH（一个假定基因，编码一个含256个氨基酸残基的多肽）也观察到了类似的抑制表型。由于大多数hns缺陷细胞的鞭毛不旋转，只有少数速度降低，所以这种抑制似乎增加了旋转鞭毛的数量，这从拴菌实验中可以观察到。ycgR和yhjH基因包含在鞭毛调节子的III类启动子中发现的共有序列，并且用lacZ融合监测它们的表达需要FlhDC。这些发现表明ycgR和yhjH与H - NS一起参与运动功能，并且是鞭毛调节子的新成员。（C）2000学术出版社
A mutation in H-NS results in non-flagellation of Escherichia coli due to a reduced expression of the flhDC master operon. We found that the hns-negative strain restored its flagellation in the presence of flhDC, although the resulting strain was still non-motile. Since the intracelluar levels of motor components MotA, MotB, and FliG in the Delta hns strain were unaltered, the non-motility indicates that H-NS affects flagellar function as well as biogenesis. We obtained an insertion in ycgR, a putative gene encoding a protein of 244 amino acid residues, which suppresses the motility defect of hns-deficient cells. The abnormally low swimming speed of hns mutant cells was fully restored by an insertion in ycgR, as assessed with computer-assisted motion analysis. A similar suppressor phenotype was observed with a multicopy expression of yhjH, a putative gene encoding a polypeptide of 256 amino acid residues. Since the flagella of most hns-deficient cells were not rotating, except a few with reduced speed, the suppression appears to increase the number of rotating flagella as observed with tethered bacteria. The ycgR and yhjH genes contain the consensus sequence found among the class III promoters of the flagellar regulon, and their expression monitored with a lacZ fusion requires FlhDC. These findings suggest that ycgR and yhjH, together with H-NS, are involved in the motor function and constitute new members of the flagellar regulon. (C) 2000 Academic Press.