Identification of an RNase J ortholog in Sulfolobus solfataricus: Implications for 5′-to-3′ directional decay and 5′-end protection of mRNA in Crenarchaeota
Identification of an RNase J ortholog in Sulfolobus solfataricus: Implications for 5′-to-3′ directional decay and 5′-end protection of mRNA in Crenarchaeota
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DOI：
10.1261/rna.2418211
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发表时间：
2011-01-01
期刊：
影响因子：
4.5
通讯作者：
Blaesi, Udo
中科院分区：
文献类型：
--
作者：
Hasenoehrl, David;Konrat, Robert;Blaesi, Udo
在细菌和真核生物中，已知降解开始于mRNA的5'端和3'端。直到最近在极端嗜热广古菌中发现了5 '-to-3'外切核糖核酸酶，外切体才被认为是嗜热广古菌中mRNA降解的关键酶。通过酶谱分析和生物信息学的方法，我们鉴定了crenarchaeum Sulfolobus solfataricus（Sso）中的一种5 '-to-3'核糖核酸外切酶活性，该活性受mRNA 5 '-末端磷酸化状态的影响。该蛋白质包含金属β-内酰胺酶的β-CASP家族的典型特征基序，并被称为Sso-RNAse J。因此，我们的研究提供了第一个证据，为在Crenarchaeal进化枝中的Crenarchaeal进化枝的5 '到3'定向mRNA衰变途径。在细菌中，mRNA的5 '端通常由三磷酸化的5'端和/或茎环结构保护，而在真核生物中，帽结合复合物负责这项任务。在这里，我们发现翻译起始因子a/eIF 2（γ）与mRNA 5 '端的结合在体外抵消了Sso-RNase J的5'至3'外切核糖核酸溶解活性。因此，5 '-至-3'定向衰变和5 '-末端保护似乎是所有生命界中mRNA周转的保守特征。
In both Bacteria and Eukaryotes, degradation is known to start at the 5' and at the 3' extremities of mRNAs. Until the recent discovery of 5'-to-3' exoribonucleases in hyperthermophilic Euryarchaeota, the exosome was assumed to be the key enzyme in mRNA degradation in Archaea. By means of zymogram assays and bioinformatics, we have identified a 5'-to-3' exoribonuclease activity in the crenarchaeum Sulfolobus solfataricus ( Sso), which is affected by the phosphorylation state of the 5'-end of the mRNA. The protein comprises typical signature motifs of the beta-CASP family of metallo-beta-lactamases and was termed Sso-RNAse J. Thus, our study provides the first evidence for a 5'-to-3' directional mRNA decay pathway in the crenarchaeal clade of Archaea. In Bacteria the 5'-end of mRNAs is often protected by a tri-phosphorylated 5'-terminus and/or by stem-loop structures, while in Eukaryotes the cap-binding complex is responsible for this task. Here, we show that binding of translation initiation factor a/eIF2(gamma) to the 5'-end of mRNA counteracts the 5'-to-3' exoribonucleolytic activity of Sso-RNase J in vitro. Hence, 5'-to-3' directional decay and 5'-end protection appear to be conserved features of mRNA turnover in all kingdoms of life.