Department of Chemistry, University of California, Davis, CA, USA.
Department of Molecular and Cellular Biology, University of California, Davis, CA, USA.
Nucleic Acids Res. 2020 Aug 20;48(14):7958-7972. doi: 10.1093/nar/gkaa532.
Adenosine deaminases acting on RNA (ADARs) are enzymes that convert adenosine to inosine in duplex RNA, a modification that exhibits a multitude of effects on RNA structure and function. Recent studies have identified ADAR1 as a potential cancer therapeutic target. ADARs are also important in the development of directed RNA editing therapeutics. A comprehensive understanding of the molecular mechanism of the ADAR reaction will advance efforts to develop ADAR inhibitors and new tools for directed RNA editing. Here we report the X-ray crystal structure of a fragment of human ADAR2 comprising its deaminase domain and double stranded RNA binding domain 2 (dsRBD2) bound to an RNA duplex as an asymmetric homodimer. We identified a highly conserved ADAR dimerization interface and validated the importance of these sequence elements on dimer formation via gel mobility shift assays and size exclusion chromatography. We also show that mutation in the dimerization interface inhibits editing in an RNA substrate-dependent manner for both ADAR1 and ADAR2.
腺苷脱氨酶作用于 RNA（ADARs）是一类酶，可将双链 RNA 中的腺苷转换为肌苷，这种修饰对 RNA 结构和功能具有多种影响。最近的研究表明 ADAR1 是一种有潜力的癌症治疗靶点。ADARs 在靶向 RNA 编辑治疗药物的开发中也很重要。全面了解 ADAR 反应的分子机制将有助于开发 ADAR 抑制剂和新的靶向 RNA 编辑工具。在此，我们报告了人 ADAR2 的一个片段的 X 射线晶体结构，该片段包含其脱氨酶结构域和双链 RNA 结合结构域 2（dsRBD2）与 RNA 双链复合物形成的非对称同源二聚体。我们鉴定了一个高度保守的 ADAR 二聚化界面，并通过凝胶迁移率变动分析和大小排阻色谱验证了这些序列元件在二聚体形成中的重要性。我们还表明，二聚化界面的突变以 RNA 底物依赖的方式抑制 ADAR1 和 ADAR2 的编辑。
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