Structure and interactions of the first three RNA recognition motifs of splicing factor Prp24
Structure and interactions of the first three RNA recognition motifs of splicing factor Prp24
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DOI：
10.1016/j.jmb.2007.01.078
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发表时间：
2007-04-13
影响因子：
5.6
通讯作者：
Brow, David A.
中科院分区：
文献类型：
--
作者：
Bae, Euiyoung;Reiter, Nicholas J.;Brow, David A.
酿酒酵母必需的前信使RNA剪接蛋白24(Prp24)具有四个RNA识别基序(RRMS)，在剪接体组装过程中促进U6 RNA与U4 RNA的碱基配对。Prp24是游离U6小核糖核蛋白颗粒(SnRNP)的组成部分，但不是U4/U6 bi-SnRNP的组成部分，因此被认为是通过U4/U6碱基配对而从U6移位的。Prp24的四个RRMS中每一个的相互作用伙伴以及这些相互作用如何指导U4/U6配对尚不清楚。这里我们报道了Prp24的前三个RRMS的晶体结构和前两个RRMS的溶液结构。值得注意的是，RRM 2与RRMS 1和3形成了广泛的结构域间接触。这些接触占据了RRMS 1和2的大部分规范RNA结合面(β-折叠)，但暴露了RRM 3的β-折叠。先前发现的Prp24中抑制U4和U6剪接体RNAs突变的替换主要聚集在RRM3的β-折叠中，但也在RRM2的保守环中。RNA结合分析和化学位移映射表明，RRMS1和2表面上明显的一个大的碱性斑块是高亲和力U6 RNA结合位点的一部分。我们的结果表明，Prp24主要与RRMS I和2结合游离U6 RNA，这可能重塑U6二级结构。然后，RRM3的β-折叠通过与未知配体的相互作用影响U4/U6配对。(C)2007爱思唯尔有限公司。保留所有权利。
The essential Saccharomyces cerevisiae pre-messenger RNA splicing protein 24 (Prp24) has four RNA recognition motifs (RRMs) and facilitates U6 RNA base-pairing with U4 RNA during spliceosome assembly. Prp24 is a component of the free U6 small nuclear ribonucleoprotein particle (snRNP) but not the U4/U6 bi-snRNP, and so is thought to be displaced from U6 by U4/U6 base-pairing. The interaction partners of each of the four RRMs of Prp24 and how these interactions direct U4/U6 pairing are not known. Here we report the crystal structure of the first three RRMs and the solution structure of the first two RRMs of Prp24. Strikingly, RRM 2 forms extensive inter-domain contacts with RRMs 1 and 3. These contacts occupy much of the canonical RNA-binding faces (beta-sheets) of RRMs 1 and 2, but leave the beta-sheet of RRM 3 exposed. Previously identified substitutions in Prp24 that suppress mutations in U4 and U6 spliceosomal RNAs cluster primarily in the beta-sheet of RRM 3, but also in a conserved loop of RRM 2. RNA binding assays and chemical shift mapping indicate that a large basic patch evident on the surface of RRMs 1 and 2 is part of a high affinity U6 RNA binding site. Our results suggest that Prp24 binds free U6 RNA primarily with RRMs I and 2, which may remodel the U6 secondary structure. The beta-sheet of RRM 3 then influences U4/U6 pairing through interaction with an unidentified ligand. (c) 2007 Elsevier Ltd. All rights reserved.