Nab2p and the Thp1p-Sac3p complex functionally interact at the interface between transcription and mRNA metabolism
Nab2p and the Thp1p-Sac3p complex functionally interact at the interface between transcription and mRNA metabolism
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DOI：
10.1074/jbc.m302900200
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发表时间：
2003-06-27
影响因子：
4.8
通讯作者：
Aguilera, A
中科院分区：
文献类型：
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作者：
Gallardo, M;Luna, R;Aguilera, A
THP 1是一种保守的真核基因，其无效突变在酵母中赋予转录和遗传不稳定性表型以及与THO/TREX复合物无效突变相似的RNA输出缺陷。在寻找thp 1Delta细胞转录缺陷的多拷贝抑制因子的过程中，我们鉴定了poly（A）（+）RNA结合的异质核核糖核蛋白Nab 2 p。多拷贝NAB 2也抑制了thp 1Delta细胞的RNA输出缺陷。这一结果表明Thp 1 p和Nab 2 p之间的功能关系。一致地，泄漏突变nab 2 -1赋予的转录缺陷和超重组表型类似的thp 1Delta，虽然在较小的程度。反过来，纯化的His 6标记的Thp 1 p融合体在体外结合RNA。在不同的方法中，我们通过Western分析表明，高度纯化的Thp 1 p-Sac 3 p复合物不含THO/TREX的组分，并且sac 3Delta赋予与thp 1Delta相同的转录缺陷和超重组表型。在thp 1Delta突变体中mRNA降解不受影响，这意味着它们的表达缺陷不是由于mRNA降解。这表明Thp 1 p-Sac 3 p是一个结构和功能单元。总之，我们的研究结果表明，Thp 1 p-Sac 3 p和Nab 2 p是功能相关的异质核核糖核蛋白，定义了mRNA代谢和转录之间的进一步联系。
THP1 is a conserved eukaryotic gene whose null mutations confer, in yeast, transcription and genetic instability phenotypes and RNA export defects similar to those of the THO/TREX complex null mutations. In a search for multicopy suppressors of the transcription defect of thp1Delta cells, we identified the poly(A)(+) RNA-binding heterogeneous nuclear ribonucleoprotein Nab2p. Multicopy NAB2 also suppressed the RNA export defect of thp1Delta cells. This result suggests a functional relationship between Thp1p and Nab2p. Consistently, the leaky mutation nab2-1 conferred a transcription defect and hyper-recombination phenotype similar to those of thp1Delta, although to a minor degree. Reciprocally, a purified His6-tagged Thp1p fusion bound RNA in vitro. In a different approach, we show by Western analyses that a highly purified Thp1p-Sac3p complex does not contain components of THO/TREX and that sac3Delta confers a transcription defect and hyper-recombination phenotype identical to those of thp1Delta. mRNA degradation was not affected in thp1Delta mutants, implying that their expression defects are not due to mRNA decay. This indicates that Thp1p-Sac3p is a structural and functional unit. Altogether, our results suggest that Thp1p-Sac3p and Nab2p are functionally related heterogeneous nuclear ribonucleoproteins that define a further link between mRNA metabolism and transcription.