The RNA degradosome and poly(A) polymerase of Escherichia coli are required in vivo for the degradation of small mRNA decay intermediates containing REP-stabilizers
The RNA degradosome and poly(A) polymerase of Escherichia coli are required in vivo for the degradation of small mRNA decay intermediates containing REP-stabilizers
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DOI：
10.1046/j.1365-2958.2003.03862.x
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发表时间：
2004-02-01
影响因子：
3.6
通讯作者：
Carpousis, AJ
中科院分区：
文献类型：
--
作者：
Khemici, V;Carpousis, AJ
在大肠杆菌中，Rep-稳定剂是多顺反子信息中的结构元件，它保护5‘-近端顺反子免受3’-gt；5‘外切核解降解。受保护顺反子的稳定性可能是基因表达水平的一个重要决定因素。我们的结果表明，核糖核酸酶E是一种内切核酸酶，它启动了rep稳定的mRNA的降解。然而，含有rep稳定剂的信使核糖核酸片段的后续降解对信使核糖核酸的降解机制提出了特殊的挑战。多核苷酸磷酸化酶(PNPase)降解Rep稳定剂需要两种酶，即DEAD-box RNA解旋酶Rh1B和多聚(A)聚合酶(PAP)。这是第一个体内证据表明这些酶是降解REP稳定剂所必需的。此外，我们的结果表明，Rh1B和PNPase降解rep需要它们作为RNA降解体的组成部分与RNase E结合，从而提供了第一个体内证据，证明这种核糖核溶解多酶复合体参与了结构化mRNA片段的降解。
In Escherichia coli, REP-stabilizers are structural elements in polycistronic messages that protect 5'-proximal cistrons from 3'-->5' exonucleolytic degradation. The stabilization of a protected cistron can be an important determinant in the level of gene expression. Our results suggest that RNase E, an endoribonuclease, initiates the degradation of REP-stabilized mRNA. However, subsequent degradation of mRNA fragments containing a REP-stabilizer poses a special challenge to the mRNA degradation machinery. Two enzymes, the DEAD-box RNA helicase, RhlB and poly(A) polymerase (PAP) are required to facilitate the degradation of REP-stabilizers by polynucleotide phosphorylase (PNPase). This is the first in vivo evidence that these enzymes are required for the degradation of REP-stabilizers. Furthermore, our results show that REP degradation by RhlB and PNPase requires their association with RNase E as components of the RNA degradosome, thus providing the first in vivo evidence that this ribonucleolytic multienzyme complex is involved in the degradation of structured mRNA fragments.