Direct interactions between the Paf1 complex and a cleavage and polyadenylation factor are revealed by dissociation of Paf1 from RNA polymerase II
Direct interactions between the Paf1 complex and a cleavage and polyadenylation factor are revealed by dissociation of Paf1 from RNA polymerase II
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DOI：
10.1128/ec.00434-07
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发表时间：
2008-07-01
期刊：
影响因子：
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通讯作者：
Jaehning, Judith A.
中科院分区：
文献类型：
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作者：
Nordick, Kristen;Hoffman, Matthew G.;Jaehning, Judith A.
Paf1复合体（Paf1、Ctr9、Cdc73、Rtf1和Leo1）在整个转录周期中通常与RNA聚合酶II （Pol II）相关。然而，Rtf1或Cdc73的缺失会导致Paf1复合物与Pol II和活性转录基因的染色质形式分离。使用功能标记形式的Paf1复合体因子，我们已经确定，除了更松散关联的Rtf1外，其余组分在与Pol II和染色质分离后，在rnase抗性复合体中保持稳定的相互关联。Paf1、Ctr9或Cdc73或Rtf1的缺失导致Pol II c端结构域的丝氨酸2磷酸化水平降低，MAK21聚腺苷化位点的读通率增加。我们发现，裂解和聚腺苷化因子Cft1需要Paf1复合物的Pol II相关形式才能与5-丝氨酸磷酸化形式的Pol II完全相互作用。当Paf1复合物与Pol II分离时，可以检测到Cft1与Paf1复合物之间的直接相互作用。这些结果与Paf1复合体在转录周期的早期点为募集3'端加工因子提供了一个接触点一致。这种连接的缺乏有助于解释在缺乏Paf1时观察到的3'端形成缺陷。
The Paf1 complex (Paf1, Ctr9, Cdc73, Rtf1, and Leo1) is normally associated with RNA polymerase II (Pol II) throughout the transcription cycle. However, the loss of either Rtf1 or Cdc73 results in the detachment of the Paf1 complex from Pol II and the chromatin form of actively transcribed genes. Using functionally tagged forms of the Paf1 complex factors, we have determined that, except for the more loosely associated Rtf1, the remaining components stay stably associated with one another in an RNase-resistant complex after dissociation from Pol II and chromatin. The loss of Paf1, Ctr9, or to a lesser extent Cdc73 or Rtf1 results in reduced levels of serine 2 phosphorylation of the Pol II C-terminal domain and in increased read through of the MAK21 polyadenylation site. We found that the cleavage and polyadenylation factor Cft1 requires the Pol II-associated form of the Paf1 complex for full levels of interaction with the serine 5-phosphorylated form of Pol II. When the Paf1 complex is dissociated from Pol II, a direct interaction between Cft1 and the Paf1 complex can be detected. These results are consistent with the Paf1 complex providing a point of contact for recruitment of 3'-end processing factors at an early point in the transcription cycle. The lack of this connection helps to explain the defects in 3'-end formation observed in the absence of Paf1.