Hori Koichi, Watanabe Yuichiro
Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Komaba, Meguro-ku, Tokyo, 153-8902 Japan.
Plant Cell Physiol. 2007 Jul;48(7):1072-8. doi: 10.1093/pcp/pcm075. Epub 2007 Jun 13.
The nonsense-mediated mRNA decay (NMD) system is an RNA surveillance system that degrades mRNAs possessing premature translation termination codons (PTCs). Although NMD factors are well conserved in eukaryotes, it is speculated that the contexts of those termination codons that are subject to NMD are different depending on the organism. Context analysis of termination codons that are recognized by the plant NMD system would clarify NMD target mRNAs in plants, and contribute to our understanding of its biological relevance in plants. In the present study we analyzed the positions of termination codons that were recognized as PTCs using an Agrobacterium transient expression assay, i.e. the accumulation of a series of plant mRNAs with nonsense mutations in different contexts was tested in plants. The results indicated that termination codons that are located distant from the mRNA 3' termini or >50 nucleotides upstream of the 3'-most exon-exon junction are recognized as substrates for NMD.
无义介导的mRNA降解（NMD）系统是一种RNA监测系统，可降解具有提前翻译终止密码子（PTC）的mRNA。尽管NMD因子在真核生物中高度保守，但据推测，那些受NMD作用的终止密码子的上下文在不同生物体中有所不同。对植物NMD系统识别的终止密码子进行上下文分析，将有助于阐明植物中的NMD靶标mRNA，并有助于我们理解其在植物中的生物学相关性。在本研究中，我们使用农杆菌瞬时表达试验分析了被识别为PTC的终止密码子的位置，即在植物中测试了一系列在不同上下文中带有无义突变的植物mRNA的积累情况。结果表明，位于远离mRNA 3'末端或3'-最外显子-外显子连接处上游>50个核苷酸处的终止密码子被识别为NMD的底物。
