Self-association of poly(A)-specific ribonuclease (PARN) triggered by the R3H domain
Self-association of poly(A)-specific ribonuclease (PARN) triggered by the R3H domain
复制标题
由 R3H 结构域触发的聚腺苷酸特异性核糖核酸酶 (PARN) 自缔合。
DOI：
10.1016/j.bbapap.2014.09.010
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发表时间：
2014-12-01
影响因子：
3.2
通讯作者：
Yan, Yong-Bin
中科院分区：
文献类型：
--
作者：
He, Guang-Jun;Yan, Yong-Bin
Poly(A)特异性核糖核酸酶(Parn)是一种含有三个RNA结合域(核酸酶、R3H和RRM域)和一个C末端结构域的死烯基核糖核酸酶。PARN通过去烯基化来调节mRNA的命运，从而参与多种生理过程。PARN主要以二聚体形式存在于稀溶液中。在这项研究中，我们发现PARN在体外和活细胞中都可以自结合成四聚体和高阶低聚物。突变和光谱分析表明，PARN寡聚是由R3H结构域触发的，这导致暴露在溶剂中的Trp219荧光团被埋在一个无法接触到溶剂的微环境中。RRM和C-末端结构域也对四聚体PARN的解离速率起着调节作用。酶分析表明，四聚并不影响含有RRM结构域的全长PARN和截短酶的催化行为，这可能是由于二聚体蛋白高度倾向于自缔合成低聚物所致。四聚显著提高了截断形式的催化活性和加工性，去掉了RRM和C-末端结构域。这一结果表明，自缔合可能是PARN获得高度调控的死烯基酶活性的调控方法之一。我们认为，自结合可能通过限制扩散促进PARN集中在靶mRNAs周围。(C)2014爱思唯尔B.V.保留所有权利。
Poly(A)-specific ribonuclease (PARN) is a deadenylase with three RNA-binding domains (the nuclease, R3H and RRM domains) and a C-terminal domain. PARN participates in diverse physiological processes by regulating mRNA fates through deadenylation. PARN mainly exists as a dimer in dilute solutions. In this research, we found that PARN could self-associate into tetramer and high-order oligomers both in vitro and in living cells. Mutational and spectroscopic analysis indicated that PARN oligomerization was triggered by the R3H domain, which led to the solvent-exposed Trp219 fluorophore to become buried in a solvent-inaccessible microenvironment. The RRM and C-terminal domains also played a role in modulating the dissociation rate of the tetrameric PARN. Enzymatic analysis indicated that tetramerization did not affect the catalytic behavior of the full-length PARN and truncated enzymes containing the RRM domain, which might be caused by the high propensity of the dimeric proteins to self-associate into oligomers. Tetramerization significantly enhanced the catalytic activity and processivity of the truncated form with the removal of the RRM and C-terminal domains. The results herein suggested that self-association might be one of the regulation methods for PARN to achieve a highly regulated deadenylase activity. We propose that self-association may facilitate PARN to concentrate around the target mRNAs by restricted diffusion. (C) 2014 Elsevier B.V. All rights reserved.