Coupled degradation of a small regulatory RNA and its mRNA targets in Escherichia coli
Coupled degradation of a small regulatory RNA and its mRNA targets in Escherichia coli
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DOI：
10.1101/gad.1127103
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发表时间：
2003-10-01
影响因子：
10.5
通讯作者：
Gottesman, S
中科院分区：
文献类型：
--
作者：
Massé, E;Escorcia, FE;Gottesman, S
RyhB是一种小的反义调控RNA，在大肠杆菌中被Fur阻遏物阻遏，并负调控至少六种编码铁结合或铁储存蛋白的mRNA。当铁是有限的，RyhB水平上升，靶mRNA迅速降解。当用转录抑制剂利福平处理细胞后测量时，RyhB非常稳定，但当整体mRNA转录继续时不稳定。我们提出，RyhB营业额耦合到并依赖于与靶mRNA的配对。mRNA靶标和RyhB的降解都依赖于RNase E，并且在降解体突变体中减慢。RyhB需要RNA分子伴侣Hfq。在没有Hfq的情况下，RyhB是不稳定的，即使在一般转录被抑制时也是如此;降解依赖于RNase E。Hfq和RNase E结合RNA上的相似位点;配对可能导致Hfq丢失并被RNase E接近。另外两种Hfq依赖的小RNA，DsrA和OxyS，在整体转录关闭时也是稳定的，而在整体转录关闭时也是不稳定的，这表明当它们的靶mRNA可用于配对时，它们也会被降解。因此，这一大类调控RNA共有一种意想不到的内在机制来关闭它们的作用。
RyhB is a small antisense regulatory RNA that is repressed by the Fur repressor and negatively regulates at least six mRNAs encoding Fe-binding or Fe-storage proteins in Escherichia coli. When Fe is limiting, RyhB levels rise, and target mRNAs are rapidly degraded. RyhB is very stable when measured after treatment of cells with the transcription inhibitor rifampicin, but is unstable when overall mRNA transcription continues. We propose that RyhB turnover is coupled to and dependent on pairing with the target mRNAs. Degradation of both mRNA targets and RyhB is dependent on RNase E and is slowed in degradosome mutants. RyhB requires the RNA chaperone Hfq. In the absence of Hfq, RyhB is unstable, even when general transcription is inhibited; degradation is dependent upon RNase E. Hfq and RNase E bind similar sites on the RNA; pairing may allow loss of Hfq and access by RNase E. Two other Hfq-dependent small RNAs, DsrA and OxyS, are also stable when overall transcription is off, and unstable when it is not, suggesting that they, too, are degraded when their target mRNAs are available for pairing. Thus, this large class of regulatory RNAs share an unexpected intrinsic mechanism for shutting off their action.