Solution structure of the N-terminal RNP domain of U1A protein: The role of C-terminal residues in structure stability and RNA binding
Solution structure of the N-terminal RNP domain of U1A protein: The role of C-terminal residues in structure stability and RNA binding
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DOI：
10.1006/jmbi.1996.0171
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发表时间：
1996-03-29
影响因子：
5.6
通讯作者：
Neuhaus, D
中科院分区：
文献类型：
--
作者：
Avis, JM;Allain, FHT;Neuhaus, D
给出了使用多维异核 NMR 测定的含有残基 2 至 117 (U1A117) 的人 U1A 剪接体蛋白片段的溶液结构。该分子的 C 末端区域在游离蛋白中比之前想象的更加有序，并且其构象与 U1 RNA 发夹 II 复合物的晶体结构中所见的构象不同。 Asp90 和 Lys98 之间的残基形成横跨 β 片层的 α 螺旋，其中残基 IIe93、IIe94 和 Met97 与 Leu44、Phe56 和 IIe58 接触。这种相互作用防止疏水性残基暴露于β-片层表面的溶剂中，从而稳定蛋白质。 RNA 结合后，螺旋 C 远离该位置，将其方向改变 135 度，以允许 Tyr13、Phe56 和 Gln54 与 RNA 的碱基堆叠，并允许 Leu44 接触 RNA。螺旋 C 在与 RNA 复合物中的新位置通过从 IIe93 和 IIe94 到 IIe58、Leu 41、Va162 和 His10 的疏水相互作用以及 Ser91 和 Thr11 之间的氢键稳定。螺旋C的运动主要涉及Thr89、Asp90和Ser91主链扭转角的变化，从而螺旋充当RNA结合表面上的“盖子”。 (C) 1996 学术出版社有限公司
The solution structure of a fragment of the human U1A spliceosomal protein containing residues 2 to 117 (U1A117) determined using multi-dimensional heteronuclear NMR is presented. The C-terminal region of the molecule is considerably more ordered in the free protein than thought previously and its conformation is different from that seen in the crystal structure of the complex with U1 RNA hairpin II. The residues between Asp90 and Lys98 form an alpha-helix that lies across the beta-sheet, with residues IIe93, IIe94 and Met97 making contacts with Leu44, Phe56 and IIe58. This interaction prevents solvent exposure of hydrophobic residues an the surface of the beta-sheet, thereby stabilising the protein. Upon RNA binding, helix C moves away from this position, changing its orientation by 135 degrees to allow Tyr13, Phe56 and Gln54 to stack with bases of the RNA, and also allowing Leu44 to contact the RNA. The new position of helix C in the complex with RNA is stabilised by hydrophobic interactions from IIe93 and IIe94 to IIe58, Leu 41, Va162 and His10, as well as a hydrogen bond between Ser91 and Thr11. The movement of helix C mainly involves changes in the main-chain torsion angles of Thr89, Asp90 and Ser91, the helix thereby acting as a ''lid'' over the RNA binding surface. (C) 1996 Academic Press Limited