MicC, a second small-RNA regulator of Omp protein expression in Escherichia coli
MicC, a second small-RNA regulator of Omp protein expression in Escherichia coli
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DOI：
10.1128/jb.186.20.6689-6697.2004
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发表时间：
2004-10-01
影响因子：
3.2
通讯作者：
Storz, G
中科院分区：
文献类型：
--
作者：
Chen, S;Zhang, AX;Storz, G
在以前的生物信息学为基础的搜索新的小RNA基因编码的大肠杆菌基因组中，我们确定了一个区域，IS 063，位于ompN和ydbK基因之间，编码一个类似于100个核苷酸的小RNA转录。在这里，我们表明，这种小RNA的表达在低温和基本培养基中增加。该转录物5'端的22个核苷酸具有与编码外膜蛋白OmpC的mRNA的前导序列形成碱基对的潜力。IS 063的缺失使ompC-luc翻译融合体的表达增加1.5至2倍，并且小RNA的10倍过表达导致融合体的2至3倍抑制。IS 063 RNA的缺失和过表达也分别导致OmpC蛋白水平的增加和减少。综上所述，这些结果表明IS 063是OmpC表达的调节因子;因此，小RNA已被重命名为MicC。发现ompC mRNA中的补偿突变抑制micC突变进一步证明了反义调节。MicC还显示在体外抑制核糖体与ompC mRNA前导序列的结合，并且需要Hfq RNA伴侣来实现其功能。我们认为MicF和MicC RNA与EnvZ-OmpR双组分系统一起作用，以控制OmpF/OmpC蛋白比例，以响应各种环境刺激。
In a previous bioinformatics-based search for novel small-RNA genes encoded by the Escherichia coli genome, we identified a region, IS063, located between the ompN and ydbK genes, that encodes an similar to100-nucleotide small-RNA transcript. Here we show that the expression of this small RNA is increased at a low temperature and in minimal medium. Twenty-two nucleotides at the 5' end of this transcript have the potential to form base pairs with the leader sequence of the mRNA encoding the outer membrane protein OmpC. The deletion of IS063 increased the expression of an ompC-luc translational fusion 1.5- to 2-fold, and a 10-fold overexpression of the small RNA led to a 2- to 3-fold repression of the fusion. Deletion and overexpression of the IS063 RNA also resulted in increases and decreases, respectively, in OmpC protein levels. Taken together, these results suggest that IS063 is a regulator of OmpC expression; thus, the small RNA has been renamed MicC. The antisense regulation was further demonstrated by the finding that micC mutations were suppressed by compensatory mutations in the ompC mRNA. MicC was also shown to inhibit ribosome binding to the ompC mRNA leader in vitro and to require the Hfq RNA chaperone for its function. We suggest that the MicF and MicC RNAs act in conjunction with the EnvZ-OmpR two-component system to control the OmpF/OmpC protein ratio in response to a variety of environmental stimuli.