Yeast Trf5p is a nuclear poly(A) polymerase
Yeast Trf5p is a nuclear poly(A) polymerase
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DOI：
10.1038/sj.embor.7400612
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发表时间：
2006-02-01
期刊：
影响因子：
7.7
通讯作者：
Tollervey, D
中科院分区：
文献类型：
--
作者：
Houseley, J;Tollervey, D
最近的研究表明，Trf4p-Air1/2p-MTR4p聚腺苷酸化(TRAMP)复合体可以刺激酵母核外切体的活性。在这里，我们报告了缺乏核外切体Rrp6p成分的菌株积累了许多不同核糖体RNA前体(前rRNAs)的多腺化形式。在缺乏聚(A)聚合酶Trf4p或其紧密同源物Trf5p的菌株中，这种多腺苷基化减少。相反，Trf5p的过表达增强了多聚腺苷的作用。在缺乏RNA解旋酶Mtr4p的菌株中，多聚腺苷酸化也显著增加，这表明它需要将聚(A)聚合酶活性与降解结合起来。串联亲和纯化标记的纯化的Trf5p在体外显示出多腺苷基化活性，这种活性被预测的催化位点的双点突变所取消。Trf5p与Mtr4p和Air1p共同纯化，表明它形成了一种复合体，命名为TRAMP5，具有与TraMP复合体部分重叠的功能。
Recent analyses have shown that the activity of the yeast nuclear exosome is stimulated by the Trf4p - Air1/ 2p - Mtr4p polyadenylation ( TRAMP) complex. Here, we report that strains lacking the Rrp6p component of the nuclear exosome accumulate polyadenylated forms of many different ribosomal RNA precursors ( pre-rRNAs). This polyadenylation is reduced in strains lacking either the poly( A) polymerase Trf4p or its close homologue Trf5p. In contrast, polyadenylation is enhanced by overexpression of Trf5p. Polyadenylation is also markedly increased in strains lacking the RNA helicase Mtr4p, indicating that it is required to couple poly( A) polymerase activity to degradation. Tandem affinity purification-tagged purified Trf5p showed polyadenylation activity in vitro, which was abolished by a double point mutation in the predicted catalytic site. Trf5p co-purified with Mtr4p and Air1p, indicating that it forms a complex, designated TRAMP5, that has functions that partially overlap with the TRAMP complex.