The small RNA RyhB activates the translation of shiA mRNA encoding a permease of shikimate, a compound involved in siderophore synthesis
The small RNA RyhB activates the translation of shiA mRNA encoding a permease of shikimate, a compound involved in siderophore synthesis
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DOI：
10.1111/j.1365-2958.2007.05733.x
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发表时间：
2007-06-01
影响因子：
3.6
通讯作者：
Masse, Eric
中科院分区：
文献类型：
--
作者：
Prevost, Karine;Salvail, Hubert;Masse, Eric
RyhB是一种小RNA（sRNA），下调约20个参与铁代谢的基因。它在低铁条件下表达，并与特定的mRNA配对，以触发RNA降解体对其的快速降解。与此相反，另一项研究表明，RyhB也通过增加mRNA水平激活几个基因。在这些被激活的基因中，shiA编码莽草酸的通透酶，莽草酸是一种参与铁载体生物合成的芳香族化合物。在这里，我们在体内和体外证明，RyhB直接配对在5 '-非翻译区（5'-UTR）的shiA mRNA破坏固有的抑制结构，隔离核糖体结合位点（Shine-Dalgarno）和第一个翻译密码子。这是RyhB直接基因激活的第一个证明，它只在mRNA的降解中被描述。我们的生理结果表明，运输化合物的ShiA通透酶，莽草酸，是重要的RyhB表达的条件下，即铁饥饿。这是证明了由莽草酸或铁载体肠螯合素纠正生长缺陷的生长测定中观察到的ryhB突变体在铁限制的媒体。
RyhB is a small RNA (sRNA) that downregulates about 20 genes involved in iron metabolism. It is expressed under low iron conditions and pairs with specific mRNAs to trigger their rapid degradation by the RNA degradosome. In contrast to this, another study has suggested that RyhB also activates several genes by increasing their mRNA level. Among these activated genes is shiA, which encodes a permease of shikimate, an aromatic compound participating in the biosynthesis of siderophores. Here, we demonstrate in vivo and in vitro that RyhB directly pairs at the 5'-untranslated region (5'-UTR) of the shiA mRNA to disrupt an intrinsic inhibitory structure that sequesters the ribosome-binding site (Shine-Dalgarno) and the first translation codon. This is the first demonstration of direct gene activation by RyhB, which has been exclusively described in degradation of mRNAs. Our physiological results indicate that the transported compound of the ShiA permease, shikimate, is important under conditions of RyhB expression, that is, iron starvation. This is demonstrated by growth assays in which shikimate or the siderophore enterochelin correct the growth defect observed for a ryhB mutant in iron-limited media.