A short conserved motif in ALYREF directs cap- and EJC-dependent assembly of export complexes on spliced mRNAs.
A short conserved motif in ALYREF directs cap- and EJC-dependent assembly of export complexes on spliced mRNAs.
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DOI：
10.1093/nar/gkw009
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发表时间：
2016-03-18
影响因子：
14.9
通讯作者：
Gehring NH
中科院分区：
文献类型：
--
作者：
Gromadzka AM;Steckelberg AL;Singh KK;Hofmann K;Gehring NH
信使RNA（mRNA）的输出是基因表达的几个核转录后步骤的最后一步。有输出能力的mRNP的形成涉及被认为促进成熟mRNA运输的输出因子的募集。使用体外剪接测定，我们表明，一组核心的出口因子，包括EJCREF，UAP56和DDX39，很容易与剪接的RNA在EJC（外显子连接复合物）和帽依赖性的方式。为了阐明BREF和其他输出衔接子如何介导mRNA输出，我们进行了计算分析，发现了RNA结合蛋白中存在的四个短的、保守的线性基序。我们发现，突变的一个新的基序（WxHD）在一个非结构化的区域，减少RNA结合，并取消了与eIF4A3和CBP 80的相互作用。此外，该突变损害了对核斑点的适当定位和剪接报告mRNA的输出。我们的研究结果揭示了重要的细节，精心策划的招聘过程中形成的出口主管mRNP的出口因素。
The export of messenger RNAs (mRNAs) is the final of several nuclear posttranscriptional steps of gene expression. The formation of export-competent mRNPs involves the recruitment of export factors that are assumed to facilitate transport of the mature mRNAs. Using in vitro splicing assays, we show that a core set of export factors, including ALYREF, UAP56 and DDX39, readily associate with the spliced RNAs in an EJC (exon junction complex)- and cap-dependent manner. In order to elucidate how ALYREF and other export adaptors mediate mRNA export, we conducted a computational analysis and discovered four short, conserved, linear motifs present in RNA-binding proteins. We show that mutation in one of the new motifs (WxHD) in an unstructured region of ALYREF reduced RNA binding and abolished the interaction with eIF4A3 and CBP80. Additionally, the mutation impaired proper localization to nuclear speckles and export of a spliced reporter mRNA. Our results reveal important details of the orchestrated recruitment of export factors during the formation of export competent mRNPs.