Implication of membrane localization of target mRNA in the action of a small RNA:: mechanism of post-transcriptional regulation of glucose transporter in Escherichia coli
Implication of membrane localization of target mRNA in the action of a small RNA:: mechanism of post-transcriptional regulation of glucose transporter in Escherichia coli
复制标题
DOI：
10.1101/gad.1270605
复制
发表时间：
2005-02-01
影响因子：
10.5
通讯作者：
Aiba, H
中科院分区：
文献类型：
--
作者：
Kawamoto, H;Morita, T;Aiba, H
葡萄糖-6-磷酸等磷酸糖的积累导致编码主要葡萄糖转运蛋白IICBGlc的ptsG mRNA以RNase E/降解体依赖性方式快速降解。ptsG mRNA的不稳定是由磷酸糖应激诱导的小反义RNA（SgrS）引起的。在这项研究中，我们分析了一系列的ptsG-CRP翻译融合，以确定快速降解ptsG mRNA所需的mRNA区域。我们发现，当ptsG-crp mRNA含有对应于IICBGlc的前两个跨膜结构域（TM 1和TM 2）的ptsG-crp mRNA的5 '部分时，其响应于磷酸糖应激而不稳定。在跨膜区的移码突变，在很大程度上消除了ptsG-crp mRNA的不稳定。含有两个以上跨膜结构域的IICBGlc-CRP融合蛋白定位于膜上。当IICBGlc的TM1和TM2被部分LacY跨膜区取代时，ptsG-crp mRNA的有效去稳定化得以恢复。我们的结论是，膜靶向性质的IICBGlc蛋白，而不是特定的核苷酸或氨基酸序列是必需的有效降解的ptsG mRNA在代谢应激。当hfq或sgrS基因失活时，ptsG-crp mRNA降解的刺激被完全消除。在没有膜定位时，通过在胞质ptsG-CRP mRNA的核糖体结合位点引入突变来减少翻译，观察到有效的mRNA不稳定。两者合计，我们得出结论，mRNA定位到内膜加上膜插入新生肽介导的Hfq/SgrS依赖的ptsG mRNA的不稳定，大概是通过减少第二轮的翻译。
Accumulation of phosphosugars such as glucose-6-phosphate causes a rapid degradation of ptsG mRNA encoding the major glucose transporter IICBGlc in an RNase E/degradosome-dependent manner. The destabilization of ptsG mRNA is caused by a small antisense RNA (SgrS) that is induced by phosphosugar stress. In this study, we analyzed a series of ptsG-crp translational fusions to identify the mRNA region required for the rapid degradation of ptsG mRNA. We found that the ptsG-crp mRNA is destabilized in response to phosphosugar stress when it contains the 5' portion of ptsG mRNA corresponding up to the first two transmembrane domains (TM1 and TM2) of IICBGlc. The destabilization of ptsG-crp mRNA was largely eliminated by frameshift mutations in the transmembrane region. The IICBGlc-CRP fusion proteins containing more than two transmembrane domains were localized at the membrane. The efficient destabilization of ptsG-crp mRNA was restored when TM1 and TM2 of IICBGlc were replaced by part of the LacY transmembrane region. We conclude that the membrane-targeting property of IICBGlc protein rather than the particular nucleotide or amino acid sequence is required for the efficient degradation of ptsG mRNA in response to metabolic stress. The stimulation of ptsG-crp mRNA degradation was completely eliminated when either the hfq or sgrS gene is inactivated. The efficient mRNA destabilization was observed in the absence of membrane localization when translation was reduced by introducing a mutation in the ribosome-binding site in the cytoplasmic ptsG-crp mRNA. Taken together, we conclude that mRNA localization to the inner membrane coupled with the membrane insertion of nascent peptide mediates the Hfq/SgrS-dependent ptsG mRNA destabilization presumably by reducing second rounds of translation.