Sørensen Brian B, Ehrnsberger Hans F, Esposito Silvia, Pfab Alexander, Bruckmann Astrid, Hauptmann Judith, Meister Gunter, Merkl Rainer, Schubert Thomas, Längst Gernot, Melzer Michael, Grasser Marion, Grasser Klaus D
Department of Cell Biology and Plant Biochemistry, Biochemistry Centre, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany.
Department for Biochemistry I, Biochemistry Centre, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany.
Plant Mol Biol. 2017 Feb;93(3):283-298. doi: 10.1007/s11103-016-0561-9. Epub 2016 Dec 21.
We identify proteins that associate with the THO core complex, and show that the TEX1 and MOS11 components functionally interact, affecting mRNA export and splicing as well as plant development. TREX (TRanscription-EXport) is a multiprotein complex that plays a central role in the coordination of synthesis, processing and nuclear export of mRNAs. Using targeted proteomics, we identified proteins that associate with the THO core complex of Arabidopsis TREX. In addition to the RNA helicase UAP56 and the mRNA export factors ALY2-4 and MOS11 we detected interactions with the mRNA export complex TREX-2 and multiple spliceosomal components. Plants defective in the THO component TEX1 or in the mRNA export factor MOS11 (orthologue of human CIP29) are mildly affected. However, tex1 mos11 double-mutant plants show marked defects in vegetative and reproductive development. In tex1 plants, the levels of tasiRNAs are reduced, while miR173 levels are decreased in mos11 mutants. In nuclei of mos11 cells increased mRNA accumulation was observed, while no mRNA export defect was detected with tex1 cells. Nevertheless, in tex1 mos11 double-mutants, the mRNA export defect was clearly enhanced relative to mos11. The subnuclear distribution of TEX1 substantially overlaps with that of splicing-related SR proteins and in tex1 plants the ratio of certain alternative splicing events is altered. Our results demonstrate that Arabidopsis TEX1 and MOS11 are involved in distinct steps of the biogenesis of mRNAs and small RNAs, and that they interact regarding some aspects, but act independently in others.
我们鉴定了与THO核心复合体相关的蛋白质，并表明TEX1和MOS11组分在功能上相互作用，影响mRNA输出和剪接以及植物发育。TREX（转录-输出）是一种多蛋白复合体，在mRNA的合成、加工和核输出的协调过程中起核心作用。利用靶向蛋白质组学，我们鉴定了与拟南芥TREX的THO核心复合体相关的蛋白质。除了RNA解旋酶UAP56以及mRNA输出因子ALY2-4和MOS11外，我们还检测到与mRNA输出复合体TREX-2和多个剪接体组分的相互作用。THO组分TEX1或mRNA输出因子MOS11（人类CIP29的直系同源物）有缺陷的植物受到的影响较小。然而，tex1 mos11双突变体植物在营养和生殖发育方面表现出明显缺陷。在tex1植物中，tasiRNA的水平降低，而在mos11突变体中miR173水平下降。在mos11细胞的细胞核中观察到mRNA积累增加，而tex1细胞未检测到mRNA输出缺陷。然而，在tex1 mos11双突变体中，相对于mos11，mRNA输出缺陷明显增强。TEX1的亚核分布与剪接相关的SR蛋白的分布基本重叠，在tex1植物中某些可变剪接事件的比例发生了改变。我们的结果表明，拟南芥TEX1和MOS11参与了mRNA和小RNA生物合成的不同步骤，它们在某些方面相互作用，但在其他方面独立发挥作用。
