Quaternary structure and catalytic activity of the Escherichia coli ribonuclease E amino-terminal catalytic domain
Quaternary structure and catalytic activity of the Escherichia coli ribonuclease E amino-terminal catalytic domain
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DOI：
10.1021/bi0351099
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发表时间：
2003-12-02
期刊：
影响因子：
2.9
通讯作者：
Luisi, BF
中科院分区：
文献类型：
--
作者：
Callaghan, AJ;Grossmann, JG;Luisi, BF
RNase E是一种重要的核糖核酸内切酶，在大肠杆菌和其他细菌中的RNA加工和降解中发挥核心作用。大多数核糖核酸内切酶已显示分布性地起作用;然而，Feng等人[（2002）Proc.Natl. Acad. sci. U.S.A.99，14746 - 14751]最近发现RNase E通过扫描机制起作用。本文对RNase E的合成能力进行了结构上的解释，并发现E. coli RNase E形成同源四聚体。非解离纳米流电喷雾质谱表明，四聚体结合了四个分子的特定底物RNA类似物。RNase E的N-末端结构域的四聚体组装与晶体学分析一致，这表明四聚体具有近似D-2二面角对称性。利用X射线溶液散射数据和对称性约束，计算了四聚体的溶液形状。这种形状，连同有限的蛋白水解数据，表明RNase E的S1-RNA结合结构域位于四聚体的外围。这些观察结果对RNase E/RNase G核糖核酸酶家族的结构和功能以及E. coliRNA降解体，其核心成分为RNase E。
RNase E is an essential endoribonuclease that plays a central role in the processing and degradation of RNA in Escherichia coli and other bacteria. Most endoribonucleases have been shown to act distributively; however, Feng et al. [(2002) Proc. Natl. Acad. Sci. U.S.A. 99, 14746-14751] have recently found that RNase E acts via a scanning mechanism. A structural explanation for the processivity of RNase E is provided here, with our finding that the conserved catalytic domain of E. coli RNase E forms a homotetramer. Nondissociating nanoflow-electrospray mass spectrometry suggests that the tetramer binds up to four molecules of a specific substrate RNA analogue. The tetrameric assembly of the N-terminal domain of RNase E is consistent with crystallographic analyses, which indicate that the tetramer possesses approximate D-2 dihedral symmetry. Using X-ray solution scattering data and symmetry restraints, a solution shape is calculated for the tetramer. This shape, together with limited proteolysis data, suggests that the Sl-RNA binding domains of RNase E lie on the periphery of the tetramer. These observations have implications for the structure and function of the RNase E/RNase G ribonuclease family and for the assembly of the E. coli RNA degradosome, in which RNase E is the central component.