The structure of the human RNase H2 complex defines key interaction interfaces relevant to enzyme function and human disease.
The structure of the human RNase H2 complex defines key interaction interfaces relevant to enzyme function and human disease.
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人RNase H2复合物的结构定义了与酶功能和人类疾病相关的关键相互作用。
DOI：
10.1074/jbc.m110.177394
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发表时间：
2011-03-25
期刊：
影响因子：
--
通讯作者：
Jackson AP
中科院分区：
文献类型：
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作者：
Reijns MA;Bubeck D;Gibson LC;Graham SC;Baillie GS;Jones EY;Jackson AP
核糖核酸酶H2（RNase H2）是参与降解RNA/DNA杂合体和去除错误掺入基因组DNA中的核糖核苷酸的主要核酶。三个RNase H2亚基中的每一个的突变都与人类自身炎症性疾病Aicardi-Goutières综合征（AGS）有关。为了了解突变如何影响RNase H2功能，我们确定了人类异源三聚体的晶体结构。在这样做的过程中，我们纠正了先前报道的小鼠RNase H2原子模型的几个关键区域，并为我们的结构模型提供了生化验证。我们的研究结果提供了新的见解如何安排的亚基，形成一个酶活性的复合物。特别是，我们确定RNASEH 2A C末端是结合两个辅助亚基的真核适应，其内具有酶活性所需的残基。该C-末端延伸与RNASEH 2C C末端相互作用，并且两者都是形成稳定的、具有酶活性的异源三聚体所必需的。疾病突变聚集在所有三个亚基之间的这个界面上，使复合物不稳定和/或损害酶活性。总的来说，我们找到了AGS患者中29个突变残基中的25个，为将来研究RNase H2酶的疾病发病机制和功能奠定了坚实的基础。
Ribonuclease H2 (RNase H2) is the major nuclear enzyme involved in the degradation of RNA/DNA hybrids and removal of ribonucleotides misincorporated in genomic DNA. Mutations in each of the three RNase H2 subunits have been implicated in a human auto-inflammatory disorder, Aicardi-Goutières Syndrome (AGS). To understand how mutations impact on RNase H2 function we determined the crystal structure of the human heterotrimer. In doing so, we correct several key regions of the previously reported murine RNase H2 atomic model and provide biochemical validation for our structural model. Our results provide new insights into how the subunits are arranged to form an enzymatically active complex. In particular, we establish that the RNASEH2A C terminus is a eukaryotic adaptation for binding the two accessory subunits, with residues within it required for enzymatic activity. This C-terminal extension interacts with the RNASEH2C C terminus and both are necessary to form a stable, enzymatically active heterotrimer. Disease mutations cluster at this interface between all three subunits, destabilizing the complex and/or impairing enzyme activity. Altogether, we locate 25 out of 29 residues mutated in AGS patients, establishing a firm basis for future investigations into disease pathogenesis and function of the RNase H2 enzyme.