Substrate recognition by ADAR1 and ADAR2
Substrate recognition by ADAR1 and ADAR2
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DOI：
10.1017/s135583820101007x
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发表时间：
2001-06-01
期刊：
影响因子：
4.5
通讯作者：
Lazinski, DW
中科院分区：
文献类型：
--
作者：
Wong, SK;Sato, S;Lazinski, DW
ADAR1 和 ADAR2 催化的 RNA 编辑涉及不完美双链 RNA 中腺苷向肌苷的位点特异性转化。 ADAR1 和 ADAR2 介导的编辑发生在大脑中谷氨酸受体 (GluR) 的转录本和肝脏中的丁型肝炎病毒 (HDV) RNA 中。尽管 ADAR2 比 ADAR1 更有效地编辑 GluR-B 前信息中的 Q/R 位点，但对于同一转录本中的 +60 位点来说，情况正好相反。 ADAR1 和 ADAR2 是具有两个共同功能区的同源物，即 N 端双链 RNA 结合结构域和 C 端脱氨酶结构域。我们既不明白为什么底物分子中只有某些腺苷作为 ADAR 的靶标，也不知道 ADAR 的哪个结构域赋予其对特定编辑位点的特异性。为了评估 RNA 序列和结构的几个方面对编辑的重要性，我们评估了来自四个编辑位点的 20 种不同的突变底物，以确定它们被 ADAR1 或 ADAR2 编辑的能力。我们发现，当这些衍生物在编辑位点包含 A:C 错配时，与同一位点出现 A:A 或 A:G 错配或 A:U 碱基对时相比，两个 ADAR 的编辑都会得到增强。因此，ADAR 的底物识别和/或催化可能涉及与编辑的腺苷相反的碱基。此外，通过使用脱氨酶结构域在 ADAR1 和 ADAR2 之间交换的蛋白质嵌合体，我们发现该结构域在定义所得酶的底物特异性方面发挥着主导作用。
RNA editing catalyzed by ADAR1 and ADAR2 involves the site-specific conversion of adenosine to inosine within imperfectly duplexed RNA. ADAR1- and ADAR2-mediated editing occurs within transcripts of glutamate receptors (GluR) in the brain and in hepatitis delta virus (HDV) RNA in the liver. Although the Q/R site within the GluR-B premessage is edited more efficiently by ADAR2 than it is by ADAR1, the converse is true for the +60 site within this same transcript. ADAR1 and ADAR2 are homologs having two common functional regions, an N-terminal double-stranded RNA-binding domain and a C-terminal deaminase domain. It is neither understood why only certain adenosines within a substrate molecule serve as targets for ADARs, nor is it known which domain of an ADAR confers its specificity for particular editing sites. To assess the importance of several aspects of RNA sequence and structure on editing, we evaluated 20 different mutated substrates, derived from four editing sites, for their ability to be edited by either ADAR1 or ADAR2. We found that when these derivatives contained an A:C mismatch at the editing site, editing by both ADARs was enhanced compared to when A:A or A:G mismatches or A:U base pairs occurred at the same site. Hence substrate recognition and/or catalysis by ADARs could involve the base that opposes the edited adenosine. In addition, by using protein chimeras in which the deaminase domains were exchanged between ADAR1 and ADAR2, we found that this domain played a dominant role in defining the substrate specificity of the resulting enzyme.