Ectopic RNase E sites promote bypass of 5′-end-dependent mRNA decay in Escherichia coli
Ectopic RNase E sites promote bypass of 5′-end-dependent mRNA decay in Escherichia coli
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DOI：
10.1046/j.1365-2958.2003.03292.x
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发表时间：
2003-01-01
影响因子：
3.6
通讯作者：
Mackie, GA
中科院分区：
文献类型：
--
作者：
Baker, KE;Mackie, GA
在大肠杆菌中，5-末端茎环形成mRNA衰变的主要障碍，但决定其有效性或使用替代衰变途径的条件尚不清楚。合成的5-末端发夹使rpsT mRNA稳定六倍。这种稳定依赖于有效的翻译起始和核糖体转运通过rpsT mRNA中的主要RNase E切割位点的至少三分之二的编码序列。将来自me前导序列或9 S pre-rRNA的12-15个残基的“异位”RNase E切割位点插入rpsTmRNA的5 '非编码区，显著降低了依赖于RNase E的末端茎环的稳定作用。类似的插入rpsT编码序列是部分不稳定的。这些发现表明RNase E可以绕过与5末端的相互作用，并利用替代的“内部进入”途径。我们提出了一个模型的rpsT mRNA的降解，这解释了不同的5 '-末端提供的保护层次，使用内部进入旁路的障碍衰变，'异位网站'和翻译核糖体的作用。
In Escherichia coli, 5-terminal stem-loops form major impediments to mRNA decay, yet conditions that determine their effectiveness or the use of alternative decay pathway(s) are unclear. A synthetic 5-terminal hairpin stabilizes the rpsT mRNA sixfold. This stabilization is dependent on efficient translational initiation and ribosome transit through at least two-thirds of the coding sequence past a major RNase E cleavage site in the rpsT mRNA. Insertion of a 12-15 residue 'ectopic' RNase E cleavage site from either the me leader or 9S pre-rRNA into the 5'-non-coding region of the rpsTmRNA significantly reduces the stabilizing effect of the terminal stem-loop, dependent on RNase E. A similar insertion into the rpsT coding sequence is partially destabilizing. These findings demonstrate that RNase E can bypass an interaction with the 5 terminus, and exploit an alternative 'internal entry' pathway. We propose a model for degradation of the rpsT mRNA, which explains the hierarchy of protection afforded by different 5'-termini, the use of internal entry for bypass of barriers to decay, 'ectopic sites' and the role of translating ribosomes.