Translation of aberrant mRNAs lacking a termination codon or with a shortened 30-UTR is repressed after initiation in yeast
Translation of aberrant mRNAs lacking a termination codon or with a shortened 30-UTR is repressed after initiation in yeast
复制标题
DOI：
10.1038/sj.emboj.7600636
复制
发表时间：
2005-04-20
期刊：
影响因子：
11.4
通讯作者：
Aiba, H
中科院分区：
文献类型：
--
作者：
Inada, T;Aiba, H
有人提出了一种新的对缺少终止密码子的mRNA的mRNA监测方法，其中Ski7p被认为识别mRNA3‘端停滞的核糖体。在这里，我们报告了我们对酿酒酵母中不间断mRNAs的翻译和衰变的分析。尽管不间断的mRNAs只减少了4.5倍，这一水平足以合成残留的蛋白质，但不间断的mRNAs的翻译产物几乎检测不到。我们发现，不间断的mRNAs与多聚体相关，但与Pab1p无关。我们还发现翻译不间断信使核糖体与信使核糖体与信使核糖体形成稳定的多聚体复合体。这些数据表明，核糖体停滞在不间断的mRNA的3‘端可能会阻止进一步的翻译，从而抑制蛋白质的合成。此外，研究还发现，在没有Ski7P的情况下，5‘-GT；3’衰变途径加速了mRNA的持续衰变。我们还发现，3‘-UTR缩短的异常mRNAs的翻译受到抑制，这表明终止密码子与mRNA 3’端之间的不适当空间距离导致了翻译抑制。
A novel mRNA surveillance for mRNA lacking a termination codon ( nonstop mRNA) has been proposed in which Ski7p is thought to recognize stalled ribosomes at the 3' end of mRNA. Here we report our analysis of translation and decay of nonstop mRNAs in Saccharomyces cerevisiae. Although the reduction of nonstop mRNAs was only 4.5-fold, a level that is sufficient for residual protein synthesis, translation products of nonstop mRNAs were hardly detectable. We show that nonstop mRNAs were associated with polysomes, but not with Pab1p. We also show that ribosomes translating nonstop mRNA formed stable and heavy polysome complexes with mRNA. These data suggest that ribosome stalling at the 3' end of nonstop mRNA may block further rounds of translation, hence repressing protein synthesis. Furthermore, it was found that the 5'-> 3' decay pathway was accelerated for nonstop mRNA decay in the absence of Ski7p. We also found that translation of aberrant mRNAs with a shortened 3'-UTR was repressed, suggesting that an improper spatial distance between the termination codon and the 3' end of mRNA results in translation repression.