A small RNA regulates the expression of genes involved in iron metabolism in Escherichia coli
A small RNA regulates the expression of genes involved in iron metabolism in Escherichia coli
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DOI：
10.1073/pnas.032066599
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发表时间：
2002-04-02
影响因子：
11.1
通讯作者：
Gottesman, S
中科院分区：
文献类型：
--
作者：
Massé, E;Gottesman, S
在大肠杆菌中寻找新型小 RNA 的全基因组研究中，发现了一种小 RNA RyhB。当铁有限时，RyhB 90-nt RNA 会下调一组铁储存和铁利用蛋白质；它本身受到铁摄取抑制蛋白 Fur（铁摄取调节剂）的负调节。 RyhB RNA 水平与 sdhCDAB 操纵子的 mRNA 水平呈负相关，sdhCDAB 操纵子编码琥珀酸脱氢酶，以及先前显示通过未知机制受 Fur 正向调节的其他五个基因。其中包括另外两个编码三羧酸循环酶的基因 acnA 和 fumA、两个铁蛋白基因 ftnA 和 bfr 以及一个超氧化物歧化酶 soda 基因。所有这些基因的 Fur 正向调节在 ryhB 突变体中完全逆转。我们的结果解释了之前观察到的毛皮突变体无法在琥珀酸上生长的现象。 RyhB 需要 RNA 结合蛋白 Hfq 才能发挥活性。 RyhB 内的序列与每个靶基因内的区域互补，表明 RyhB 作为反义 RNA。在sdhCDAB中，互补区位于sdhCDAB操纵子第一个基因的末端；当 RyhB 表达时，全长 sdhCDAB 消息消失，并且检测到截短的消息，其大小相当于互补性上游区域。 RyhB 提供了一种机制，使细胞在铁受到限制时下调铁储存蛋白和非必需含铁蛋白，从而调节细胞内铁的使用，以补充由毛皮直接调节的铁吸收机制。
A small RNA, RyhB, was found as part of a genomewide search for novel small RNAs in Escherichia coli. The RyhB 90-nt RNA down-regulates a set of iron-storage and iron-using proteins when iron is limiting; it is itself negatively regulated by the ferric uptake repressor protein, Fur (Ferric uptake regulator). RyhB RNA levels are inversely correlated with mRNA levels for the sdhCDAB operon, encoding succinate dehydrogenase, as well as five other genes previously shown to be positively regulated by Fur by an unknown mechanism. These include two other genes encoding enzymes in the tricarboxylic acid cycle, acnA and fumA, two ferritin genes, ftnA and bfr, and a gene for superoxide dismutase, soda. Fur positive regulation of all these genes is fully reversed in an ryhB mutant. Our results explain the previously observed inability of fur mutants to grow on succinate. RyhB requires the RNA-binding protein, Hfq, for activity. Sequences within RyhB are complementary to regions within each of the target genes, suggesting that RyhB acts as an antisense RNA. In sdhCDAB, the complementary region is at the end of the first gene of the sdhCDAB operon; full-length sdhCDAB message disappears and a truncated message, equivalent in size to the region upstream of the complementarity, is detected when RyhB is expressed. RyhB provides a mechanism for the cell to down-regulate iron-storage proteins and nonessential iron-containing proteins when iron is limiting, thus modulating intracellular iron usage to supplement mechanisms for iron uptake directly regulated by Fur.