Structural Basis for Substrate Helix Remodeling and Cleavage Loop Activation in the Varkud Satellite Ribozyme
Structural Basis for Substrate Helix Remodeling and Cleavage Loop Activation in the Varkud Satellite Ribozyme
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DOI：
10.1021/jacs.7b03655
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发表时间：
2017-07-19
影响因子：
15
通讯作者：
Piccirilli, Joseph A.
中科院分区：
文献类型：
--
作者：
DasGupta, Saurja;Suslov, Nikolai B.;Piccirilli, Joseph A.
Varkud卫星（VS）核酶催化位点特异性RNA切割和连接反应。底物的识别涉及底物与核酶的催化结构域之间的吻环相互作用，导致底物螺旋寄存器重排成所谓的“移位”构象，这对底物结合和活化至关重要。我们报告了一个3.3埃晶体结构的完整的核酶，揭示了活跃的，移动构象的基板，停靠到催化结构域的核酶。比较以前的NMR结构的隔离，无活性的基板提供了一个物理描述基板重塑，并暗示作用三级相互作用的催化活化的裂解环。与发夹核酶切割环激活的相似性表明了增强RNA折叠和核酶切割中的保真度的一般策略。
The Varkud satellite (VS) ribozyme catalyzes site-specific RNA cleavage and ligation reactions. Recognition of the substrate involves a kissing loop interaction between the substrate and the catalytic domain of the ribozyme, resulting in a rearrangement of the substrate helix register into a so-called "shifted" conformation that is critical for substrate binding and activation. We report a 3.3 angstrom crystal structure of the complete ribozyme that reveals the active, shifted conformation of the substrate, docked into the catalytic domain of the ribozyme. Comparison to previous NMR structures of isolated, inactive substrates provides a physical description of substrate remodeling, and implicates roles for tertiary interactions in catalytic activation of the cleavage loop. Similarities to the hairpin ribozyme cleavage loop activation suggest general strategies to enhance fidelity in RNA folding and ribozyme cleavage.