Crowding Promotes the Switch from Hairpin to Pseudoknot Conformation in Human Telomerase RNA
Crowding Promotes the Switch from Hairpin to Pseudoknot Conformation in Human Telomerase RNA
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DOI：
10.1021/ja2035128
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发表时间：
2011-08-10
影响因子：
15
通讯作者：
Thirumalai, D.
中科院分区：
文献类型：
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作者：
Denesyuk, Natalia A.;Thirumalai, D.
在核糖核蛋白人类端粒酶的保守RNA核心结构域中形成假结（PK）是其功能所必需的。体外实验表明，PK与延伸发夹（HP）结构处于平衡状态。我们使用粗粒度模型的分子模拟，该模型再现了PK和HP的实验熔解曲线的大部分显著特征，以表明拥挤增强了PK相对于HP在野生型和与先天性角化不良相关的突变体中的稳定性。在单分散悬浮液中，小的拥挤颗粒比大的拥挤颗粒更大程度地增加紧凑结构的稳定性。如果二元混合物中拥挤物的大小小于未折叠RNA的大小，则由于两种组分而导致的解链温度的增加是相加的。在一个三元混合物的拥挤是大于未折叠的RNA，这模仿组成的核糖体，大酶复合物和蛋白质在大肠杆菌，边际增加稳定性完全是由最小的组件，我们预测，拥挤可以部分恢复端粒酶活性的突变体与PK稳定性下降。
Formation of a pseudoknot (PK) in the conserved RNA core domain in the ribonucleoprotein human telomerase is required for function. In vitro experiments show that the PK is in equilibrium with an extended hairpin (HP) structure. We use molecular simulations of a coarse-grained model, which reproduces most of the salient features of the experimental melting profiles of PK and HP, to show that crowding enhances the stability of PK relative to HP in the wild type and in a mutant associated with dyskeratosis congenita. In monodisperse suspensions, small crowding particles increase the stability of compact structures to a greater extent than larger crowders. If the sizes of crowders in a binary mixture are smaller than that of the unfolded RNA, the increase in melting temperature due to the two components is additive. In a ternary mixture of crowders that are larger than the unfolded RNA, which mimics the composition of ribosome, large enzyme complexes and proteins in Escherichia cob, the marginal increase in stability is entirely determined by the smallest component We predict that crowding can partially restore telomerase activity in mutants with decreased PK stability.