The nuclear poly(A) binding protein of mammals, but not of fission yeast, participates in mRNA polyadenylation.
The nuclear poly(A) binding protein of mammals, but not of fission yeast, participates in mRNA polyadenylation.
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DOI：
10.1261/rna.057026.116
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发表时间：
2017-04
期刊：
影响因子：
--
通讯作者：
Wahle E
中科院分区：
文献类型：
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作者：
Kühn U;Buschmann J;Wahle E
核多聚腺苷酸结合蛋白（PABPN 1）已被建议，在生化证据的基础上，发挥作用，在mRNA的聚腺苷酸化强烈增加的聚腺苷酸聚合酶的持续合成能力。虽然在后生动物中的实验倾向于支持这种作用，但结果并不明确，遗传数据显示，S。Pab 2是PABPN 1的粟酒酵母同源物，不参与mRNA的多聚腺苷酸化。PABPN 1增加聚（A）尾延长速率的特定模型从未在体内检查过。在这里，我们使用4-硫代尿苷脉冲标记来检查人类细胞中新合成的poly（A）尾的长度。PABPN 1的敲除强烈减少了全长尾的10250个核苷酸的合成，从生化数据预测。我们还纯化了S。pombe Pab 2和S. pombe poly（A）polymerase，Pla 1，并检测其体外活性。尽管PABPN 1在体外强烈增加其同源poly（A）聚合酶的活性，但Pab 2无法在任何显着程度上刺激Pla 1。因此，体外和体内数据一致支持PABPN 1而不是S的作用。粟酒酵母Pab 2在mRNA前体的多聚腺苷酸化中的作用。
The nuclear poly(A) binding protein (PABPN1) has been suggested, on the basis of biochemical evidence, to play a role in mRNA polyadenylation by strongly increasing the processivity of poly(A) polymerase. While experiments in metazoans have tended to support such a role, the results were not unequivocal, and genetic data show that the S. pombe ortholog of PABPN1, Pab2, is not involved in mRNA polyadenylation. The specific model in which PABPN1 increases the rate of poly(A) tail elongation has never been examined in vivo. Here, we have used 4-thiouridine pulse-labeling to examine the lengths of newly synthesized poly(A) tails in human cells. Knockdown of PABPN1 strongly reduced the synthesis of full-length tails of ∼250 nucleotides, as predicted from biochemical data. We have also purified S. pombe Pab2 and the S. pombe poly(A) polymerase, Pla1, and examined their in vitro activities. Whereas PABPN1 strongly increases the activity of its cognate poly(A) polymerase in vitro, Pab2 was unable to stimulate Pla1 to any significant extent. Thus, in vitro and in vivo data are consistent in supporting a role of PABPN1 but not S. pombe Pab2 in the polyadenylation of mRNA precursors.