Temperature-sensitive mutants of the exosome subunit Rrp43p show a deficiency in mRNA degradation and no longer interact with the exosome
Temperature-sensitive mutants of the exosome subunit Rrp43p show a deficiency in mRNA degradation and no longer interact with the exosome
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DOI：
10.1093/nar/gkf545
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发表时间：
2002-10-01
影响因子：
14.9
通讯作者：
Zanchin, NIT
中科院分区：
文献类型：
--
作者：
Oliveira, CC;Gonzales, FA;Zanchin, NIT
Rrp 43 p是酿酒酵母外泌体亚基，参与前rRNA加工，其在细胞核和细胞质中均存在。到目前为止，没有功能已被分配到Rrp 43 p的细胞质部分。我们通过分析三种rrp 43温度敏感（ts）菌株（它们携带不同的ts等位基因（rrp 43 -1，rrp 43 -2和rrp 43 -3））的mRNA稳定性，并通过分析Rrp 43 p与其余外泌体亚基的相互作用，来解决Rrp 43 p的功能。在ts菌株中，相对于携带野生型RRP 43的对照菌株，内源性mRNA（ACT 1和PAB 1）以及异源报告mRNA（CATpG）显示出更长的半衰期。突变体还积累了报告mRNA的降解中间体，这是典型的缺陷mRNA衰变。这些结果使我们能够提出Rrp 43 p是mRNA降解所需的。如通过双杂交分析所确定的，Rrp 43 p通过Rrp 46 p与外泌体复合物相互作用。有趣的是，rrp 43 ts突变蛋白不与Rrp 46 p相互作用，表明ts表型可能是由Rrp 43 p-Rrp 46 p相互作用的破坏引起的。ts菌株还显示出前rRNA加工缺陷，这与先前对Rrp 43 p功能的研究一致。
Rrp43p is a Saccharomyces cerevisiae exosome subunit involved in pre-rRNA processing which is found both in the nucleus and in the cytoplasm. So far, no function has been assigned to the cytoplasmic fraction of Rrp43p. We have addressed Rrp43p function by analyzing mRNA stability in three rrp43 temperature-sensitive (ts) strains, which carry different ts alleles (rrp43-1, rrp43-2 and rrp43-3), and by analyzing Rrp43p interactions with the remaining exosome subunits. In the ts strains, endogenous mRNAs (ACT1 and PAB1), as well as a heterologous reporter mRNA (CATpG) showed longer half-lives, relative to a control strain carrying wild-type RRP43. The mutants also accumulated a degradation intermediate of the reporter mRNA that is typical of defective mRNA decay. These results allow us to propose that Rrp43p is required for mRNA degradation. Rrp43p interacts with the exosome complex via Rrp46p, as determined by two-hybrid analyses. Interestingly, the rrp43 ts mutant proteins do not interact with Rrp46p, indicating that the ts phenotype may be caused by disruption of the Rrp43p- Rrp46p interaction. The ts strains also showed a pre-rRNA processing defect, which is consistent with previous studies on Rrp43p function.