The RNA-editing enzyme ADAR1 is localized to the nascent ribonucleoprotein matrix on Xenopus lampbrush chromosomes but specifically associates with an atypical loop
The RNA-editing enzyme ADAR1 is localized to the nascent ribonucleoprotein matrix on Xenopus lampbrush chromosomes but specifically associates with an atypical loop
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DOI：
10.1083/jcb.144.4.603
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发表时间：
1999-02-22
影响因子：
7.8
通讯作者：
Jantsch, MF
中科院分区：
文献类型：
--
作者：
Eckmann, CR;Jantsch, MF
双链RNA腺苷脱氨酶(ADAR1，dsRAD，DRADA)在双链RNA中将腺苷转化为肌苷。目前已知的ADAR1编辑的候选底物很少，也不知道底物识别是如何实现的。在某些情况下，编辑位点是由内含子和外显子序列之间形成的碱基区域定义的，这表明该酶可能具有共转录功能。我们已经分离出非洲爪哇ADAR1的两个变种，目前尚不知道其编辑底物。我们证明了这两种酶的变种都与转录活跃的染色体环有关，这表明这种酶是协同转录的。蛋白质在整个染色体上的广泛分布表明ADAR1以一种底物无关的方式与RNP基质结合。抑制剪接是另一个共转录过程，不影响ADAR1的染色体定位，此外，我们可以证明该酶在一个特殊的含有RNA的环上显著富含，该环似乎在转录上是沉默的。对这个环路的详细分析表明，它可能代表了ADAR1的存储地点，或者是正在进行活跃RNA编辑的地点。最后，ADAR1的突变分析表明，ADAR1中假定的Z-DNA结合域不是蛋白质染色体靶向所必需的。
Double-stranded RNA adenosine deaminase (ADAR1, dsRAD, DRADA) converts adenosines to inosines in double-stranded RNAs. Few candidate substrates for ADAR1 editing are known at this point and it is not known how substrate recognition is achieved. In some cases editing sites are defined by basepaired regions formed between intronic and exonic sequences, suggesting that the enzyme might function cotranscriptionally. We have isolated two variants of Xenopus laevis ADAR1 for which no editing substrates are currently known. We demonstrate that both Variants of the enzyme are associated with transcriptionally active chromosome loops suggesting that the enzyme acts cotranscriptionally. The widespread distribution of the protein along the entire chromosome indicates that ADAR1 associates with the RNP matrix in a substrate-independent manner. Inhibition of splicing, another cotranscriptional process, does not affect the chromosomal localization of ADAR1, Furthermore, we can show that the enzyme is dramatically enriched on a special RNA-containing loop that seems transcriptionally silent. Detailed analysis of this loop suggests that it might represent a site of ADAR1 storage or a site where active RNA editing is taking place. Finally, mutational analysis of ADAR1 demonstrates that a putative Z-DNA binding domain present in ADAR1 is not required for chromosomal targeting of the protein.