CONTROL OF RNASE-E-MEDIATED RNA DEGRADATION BY 5'-TERMINAL BASE-PAIRING IN ESCHERICHIA-COLI
CONTROL OF RNASE-E-MEDIATED RNA DEGRADATION BY 5'-TERMINAL BASE-PAIRING IN ESCHERICHIA-COLI
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DOI：
10.1038/360488a0
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发表时间：
1992-12-03
期刊：
影响因子：
64.8
通讯作者：
BELASCO, JG
中科院分区：
文献类型：
--
作者：
BOUVET, P;BELASCO, JG
尽管信使RNA在细菌中的半衰期各不相同（在大肠杆菌中为0.5-30分钟）及其在控制基因表达中的重要性，但它们的分子基础仍然不清楚。整个 mRNA 分子的寿命可以通过其 5' 末端附近的特征来确定，但在任何原核生物中尚未鉴定出 5' 外切核糖核酸酶 1-6。使大肠杆菌 RNase E 失活的突变也会增加大量大肠杆菌 mRNA 和许多单独信息的平均寿命，表明这种核酸内切酶的切割可能是大肠杆菌7-16 中大多数 mRNA 降解的速率决定步骤。我们通过使用 RNA I 的变体研究了大肠杆菌中 RNase E 的底物偏好，RNA I 是一种小的非翻译 RNA，其在体内的快速降解是由内部位点的 RNase E 裂解引发的。我们在此报告，RNase E 对核糖核酸内切酶具有前所未有的底物特异性，因为它优先切割 5' 端具有多个未配对核苷酸的 RNA。 RNase E 对 5' 端碱基配对的敏感性可以解释 5' 端附近的决定簇如何控制细菌中 mRNA 的衰减速率。
DESPITE the variety of messenger RNA half-lives in bacteria (0.5-30 min in Escherichia coli) and their importance in controlling gene expression, their molecular basis remains obscure. The life-time of an entire mRNA molecule can be determined by features near,its 5' end, but no 5' exoribonuclease has been identified in any prokaryotic organism1-6. A mutation that inactivates E. coli RNase E also increases the average lifetime of bulk E. coli mRNA and of many individual messages, suggesting that cleavage by this endonuclease may be the rate-determining step in the degradation of most mRNAs in E. coli7-16. We have investigated the substrate preference of RNase E in E. coli by using variants of RNA I, a small untranslated RNA whose swift degradation in vivo is initiated by RNase E cleavage at an internal site. We report here that RNase E has an unprecedented substrate specificity for an endoribonuclease, as it preferentially cleaves RNAs that have several unpaired nucleotides at the 5' end. The sensitivity of RNase E to 5'-terminal base pairing may explain how determinants near the 5' end can control rates of mRNA decay in bacteria.