Initiation of RNA decay in Escherichia coli by 5′ pyrophosphate removal
Initiation of RNA decay in Escherichia coli by 5′ pyrophosphate removal
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DOI：
10.1016/j.molcel.2007.05.038
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发表时间：
2007-07-06
期刊：
影响因子：
16
通讯作者：
Belasco, Joel G.
中科院分区：
文献类型：
--
作者：
Celesnik, Helena;Deana, Atilio;Belasco, Joel G.
通常认为内切核酸裂解是大肠杆菌中mRNA衰变的初始、速率决定步骤，但这不能解释5 '末端对初级转录物半衰期的影响。我们已经重新检查了在该生物体中的RNA降解的初始事件，通过设计一种测定来探测RNA的5 '磷酸化状态，并通过采用自切割锤头状核酶来研究未磷酸化的5 '末端的降解后果。这些研究已经确定了一个以前未被认识到的衰变前步骤，该步骤触发了核酸内切酶RNase E的后续内部切割，从而控制RNA寿命：三磷酸化的5 '末端向单磷酸化的5 '末端的速率决定性转化。我们的研究结果重新定义了RNase E在RNA降解中的作用，并解释了未配对的5 '端核苷酸如何促进初级转录物内的内部切割位点。此外，这些结果揭示了原核生物和真核生物中mRNA衰变机制之间的惊人相似之处。
The common belief that endonucleolytic cleavage is the initial, rate-determining step of mRNA decay in Escherichia coli fails to explain the influence of 5 ' termini on the half-lives of primary transcripts. We have re-examined the initial events of RNA degradation in that organism by devising an assay to probe the 5 ' phosphorylation state of RNA and by employing a self-cleaving hammerhead ribozyme to investigate the degradative consequences of an unphosphorylated 5 ' end. These studies have identified a previously unrecognized prior step in decay that triggers subsequent internal cleavage by the endonuclease RNase E and thereby governs RNA longevity: the rate-determining conversion of a triphosphorylated to a monophosphorylated 5 ' terminus. Our findings redefine the role of RNase E in RNA degradation and explain how unpaired 5 '-terminal nucleotides can facilitate access to internal cleavage sites within primary transcripts. Moreover, these results reveal a striking parallel between the mechanisms of mRNA decay in prokaryotic and eukaryotic organisms.