Price S R, Evans P R, Nagai K
MRC Laboratory of Molecular Biology, Cambridge, UK.
Nature. 1998 Aug 13;394(6694):645-50. doi: 10.1038/29234.
We have determined the crystal structure at 2.4 A resolution of a ternary complex between the spliceosomal U2B"/U2A' protein complex and hairpin-loop IV of U2 small nuclear RNA. Unlike its close homologue the U1A protein, U2B" binds to its cognate RNA only in the presence of U2A', which contains leucine-rich repeats in its sequence. The concave surface of a parallel beta-sheet within the leucine-rich-repeat region of U2A' interacts with the ribonucleoprotein domain of U2B" on the surface opposite its RNA-binding surface. The basic carboxy-terminal region of U2A' interacts with the RNA stem. The crystal structure reveals how protein-protein interaction regulates RNA-binding specificity, and how replacing only a few key residues allows the U2B" and U1A proteins to discriminate between their cognate RNA hairpins by forming alternative networks of interactions.
我们已经确定了剪接体U2B″/U2A′蛋白复合物与U2小核RNA的发夹环IV之间三元复合物在2.4埃分辨率下的晶体结构。与它的紧密同源物U1A蛋白不同，U2B″仅在U2A′存在时才与其同源RNA结合，U2A′的序列中含有富含亮氨酸的重复序列。U2A′富含亮氨酸重复区域内平行β折叠的凹面，在U2B″与RNA结合表面相对的表面上，与U2B″的核糖核蛋白结构域相互作用。U2A′的碱性羧基末端区域与RNA茎相互作用。晶体结构揭示了蛋白质-蛋白质相互作用如何调节RNA结合特异性，以及仅替换几个关键残基如何使U2B″和U1A蛋白通过形成不同的相互作用网络来区分它们的同源RNA发夹。
