Cytoplasmic poly(A) polymerases mediate cellular responses to S phase arrest
Cytoplasmic poly(A) polymerases mediate cellular responses to S phase arrest
复制标题
DOI：
10.1073/pnas.192467799
复制
发表时间：
2002-09-17
影响因子：
11.1
通讯作者：
Norbury, CJ
中科院分区：
文献类型：
--
作者：
Read, RL;Martinho, RG;Norbury, CJ
S-M检查点延迟有丝分裂直到DNA复制完成;当DNA复制被抑制时，在该检查点缺陷的细胞失去活力。这种失活性可以在裂殖酵母中通过Cid 1或相关蛋白Cid 13的过表达来抑制。裂变酵母含有六个类似于TRF 1/TRF 13的基因，而芽殖酵母只有两个，TRF 4和TRF 5。最近报道Trf 4和Trf 5包含建立姐妹染色单体凝聚所需的必需DNA聚合酶活性。相反，我们发现Cid 1不是DNA聚合酶，而是使用RNA底物并具有poly（A）聚合酶活性。与先前表征的酵母poly（A）聚合酶（其是核酶）不同，Cid 1和Cid 13是组成性细胞质的。Cid 1在体外具有一定程度的底物特异性，这与其靶向细胞质mRNA的子集用于体内聚腺苷酸化的概念一致，因此增加了它们的稳定性和/或翻译效率。优选的Cid 1靶标可能包括编码S-M检查点组分的mRNA，而Cid 13靶标可能参与dNTP代谢。细胞质多聚腺苷酸化是动物早期发育过程中的一种重要调控机制。我们在酵母中的发现表明，这种水平的基因调控在真核细胞中具有更普遍的意义。
The S-M checkpoint delays mitosis until DNA replication is complete; cells defective in this checkpoint lose viability when DNA replication is inhibited. This inviability can be suppressed in fission yeast by overexpression of Cid1 or the related protein Cid13. Fission yeast contain six cid1/cid13-like genes, whereas budding yeast has just two, TRF4 and TRF5. Trf4 and Trf5 were recently reported to comprise an essential DNA polymerase activity required for the establishment of sister chromatid cohesion. In contrast, we find that Cid1 is not a DNA polymerase but instead uses RNA substrates and has poly(A) polymerase activity. Unlike the previously characterized yeast poly(A) polymerase, which is a nuclear enzyme, Cid1 and Cid13 are constitutively cytoplasmic. Cid1 has a degree of substrate specificity in vitro, consistent with the notion that it targets a subset of cytoplasmic mRNAs for polyadenylation in vivo, hence increasing their stability and/or efficiency of translation. Preferred Cid1 targets presumably include mRNAs encoding components of the S-M checkpoint, whereas Cid13 targets are likely to be involved in dNTP metabolism. Cytoplasmic polyadenylation is known to be an important regulatory mechanism during early development in animals. Our findings in yeast suggest that this level of gene regulation is of more general significance in eukaryotic cells.