A three-dimensional model of a group II intron RNA and its interaction with the intron-encoded reverse transcriptase
A three-dimensional model of a group II intron RNA and its interaction with the intron-encoded reverse transcriptase
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DOI：
10.1016/j.molcel.2008.04.001
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发表时间：
2008-05-23
期刊：
影响因子：
16
通讯作者：
Zimmerly, Steven
中科院分区：
文献类型：
--
作者：
Dai, Lixin;Chai, Dinggeng;Zimmerly, Steven
第二组内含子是自剪接核酶，被认为是剪接体内含子的祖先。许多第二组内含子编码逆转录酶，促进RNA剪接和内含子迁移到新的基因组位置。在这里，我们使用循环排列和交联法在可移动的乳酸乳球菌Ll.LtrB-Delta ORF内含子内建立了16个分子内距离关系。使用这些新的限制条件，再加上13个已建立的三级相互作用和8个已发表的交联链，我们模拟了内含子的完整三维结构。我们还使用了循环排列策略，通过荧光猝灭和交联实验绘制了RNA-蛋白质相互作用位点的图谱。我们的模型为理解第二组核酶的功能、它们的自然结构变异以及内含子编码的蛋白质促进RNA剪接和内含子迁移的机制提供了一个全面的结构框架。该模型还提出了剪接体中可能保守的活性位点元件的排列。
Group II introns are self-splicing ribozymes believed to be the ancestors of spliceosomal introns. Many group II introns encode reverse transcriptases that promote both RNA splicing and intron mobility to new genomic sites. Here we used a circular permutation and crosslinking method to establish 16 intramolecular distance relationships within the mobile Lactococcus lactis Ll.LtrB-Delta ORF intron. Using these new constraints together with 13 established tertiary interactions and eight published crosslinks, we modeled a complete three-dimensional structure of the intron. We also used the circular permutation strategy to map RNA-protein interaction sites through fluorescence quenching and crosslinking assays. Our model provides a comprehensive structural framework for understanding the function of group II ribozymes, their natural structural variations, and the mechanisms by which the intron-encoded protein promotes RNA splicing and intron mobility. The model also suggests an arrangement of active site elements that may be conserved in the spliceosome.