有证据表明,热力学上不同的Mg2+离子与RNA三级结构的形成有关
Desirae Leipply1, David E Draper
1Department of Biophysics, Johns Hopkins University Baltimore, Maryland 21218, United States.
Journal of the American Chemical Society
|July 23, 2011
概括
研究人员量化了离子 (Mg2+) 与RNA的结合,揭示了特定的化部位对RNA稳定性有重大贡献. 这项工作将Mg2+化与RNA折叠脱,以进行精确的能量测量.
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:
- RNA折叠是由,特别是离子 (Mg2+) 稳定,这些离子中和埋藏的酸盐电荷.
- 由于合折叠和离子相互作用,直接测量Mg2+-RNA相互作用能量具有挑战性.
- 假设RNA三级结构内的特定Mg2+化位点对稳定至关重要.
研究的目的:
- 量化RNA中的特定Mg2+化位点的能量贡献.
- 开发将Mg2+化脱离RNA折叠和批量离子效应的方法.
- 为了估计特定地点和总Mg2+-RNA相互作用的自由能量.
主要方法:
- 利用一种高亲和度的热友性核糖体蛋白来稳定一个58mer rRNA片段.
- 捕获了rRNA在一个接近本地结构,允许解决Mg2+结合事件.
- 进行了Mg2+定位实验,以测量结合亲和力和自由能量.
主要成果:
- 确定并量化了Mg2+与稳定rRNA片段中的特定合位的结合.
- 估计0.1 mM Mg2+和60 mM K+的位点特定的Mg2+结合自由能量为~-3 kcal/mol.
- 确定特定部位的结合在较高的Mg2+度下,在总Mg2+-RNA相互作用能量中所贡献的比例较小.
结论:
- 特定的Mg2+化位在RNA三级结构稳定中发挥着显著的,可量化的作用.
- 特定的Mg2+结合的能量贡献取决于整体离子条件.
- 这项研究为测量特定位点的离子-RNA相互作用提供了一个框架.
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Different Types of RNA Have the Same Basic Structure
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The basic structure of RNA consists of a five-carbon sugar and one of four nitrogenous bases. Although most RNA is single-stranded, it can form complex secondary and tertiary structures. Such structures play essential roles in the regulation of transcription and translation.
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