5'-->3'外核酶Rat1及其激活伙伴Rai1的结构和功能
Song Xiang1, Amalene Cooper-Morgan, Xinfu Jiao
1Department of Biological Sciences, Columbia University, New York, New York 10027, USA.
Nature
|February 6, 2009
概括
这项研究揭示了Rai1如何激活Rat1外核糖酶,增强其降解RNA的能力. 这项研究揭示了Rai1中一种新的pyrophosphohydrolase活性,这表明在真核RNA代谢中具有新的作用.
科学领域:
- 生物化学 生物化学
- 分子生物学分子生物学
- 结构生物学 结构生物学
背景情况:
- 5'-->3'外核糖酶 (XRNs) 对于RNA代谢和核生物的干扰至关重要.
- XRN2 (酵母中的Rat1) 在核中起作用,对由RNA聚合酶II的转录终止至关重要.
- 已知Rat1的外皮核糖酶活性是由 Rai1.1 蛋白刺激的.
研究的目的:
- 为了阐明由 Rai1.1 激活 Rat1 的分子机制.
- 为了确定Rat1的外核酶活性的结构基础.
- 研究 Rai1/Dom3Z 在RNA代谢中的潜在新功能.
主要方法:
- 使用X射线晶体学来确定与Rai1复合的Schizosaccharomyces pombe Rat1的结构,以及单独的Rai1和小鼠Dom3Z的结构.
- 进行了生物化学测定,以确认结构观察并评估外核糖酶活性.
- 用位点定向突变发生法来研究 Rai1.1 中保存残留物的功能.
主要成果:
- 晶体结构揭示了Rai1激活Rat1并赋予Rat1独有的外原核酶活性的机制.
- Rai1被证明可以增强Rat1对具有稳定的二次结构的RNA的降解.
- 研究人员发现了Rai1对5'三化RNA的一种新型酸酸酶活性,其残留物被保存在一个独特的口袋中,协调一个双价离子.
结论:
- Rai1作为Rat1外核糖酶的关键激活剂,对该机制有结构性的洞察力.
- 这些发现表明,Rai1/Dom3Z可能在真核RNA代谢中具有额外的,以前未知的功能,特别是在处理5'三酸化RNA时.
- 这项研究扩大了我们对RNA降解途径和XRN家族酶在真核生物中的作用的理解.
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