Transcription termination by the eukaryotic RNA polymerase III.
Transcription termination by the eukaryotic RNA polymerase III.
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DOI：
10.1016/j.bbagrm.2012.10.006
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发表时间：
2013-03
影响因子：
4.7
通讯作者：
Maraia, Richard J.
中科院分区：
文献类型：
--
作者：
Arimbasseri, Aneeshkumar G.;Rijal, Keshab;Maraia, Richard J.
RNA聚合酶(Pol)III转录大量tRNA和5S rRNA基因以及分布在基因组中的其他小RNA基因。通过序列特异性、准确和高效的PolIII转录终止，不仅定义了新生RNA的3‘端，从而指导随后与稳定的La蛋白的结合，还防止转录进入下游DNA，促进有效的循环。每种RNA聚合酶似乎都进化出独特的机制来启动终止过程，以响应不同类型的终止信号。然而，在真核生物中，人们对终止的最后阶段知之甚少，即随着RNA和DNA从聚合酶活性中心释放而使延伸复合体不稳定。与Pols I和Pols II相比，PolIII在终止的初始和最后阶段表现出最直接的耦合，这两个阶段都发生在DNA的非模板链(模板上的da)上的短寡核苷酸(DT)区段。虽然POLIII的终止是自主的，涉及核心亚单位C2和可能的C1，但它也涉及作用于POLIII催化中心的C11、C37和C53亚基，分别与POLII延伸因子TFIIS和TFIIFα/β同源。在这里，我们汇编了POLIII终止的知识，并将影响这一过程的突变与聚合酶的结构元件相关联，这些结构元件说明了C53/37在其在POLIII叶上的对接位置和在活性中心中的重要性。这些模型表明，这些特征中的一些可能适用于其他真核生物的POL。
RNA polymerase (pol) III transcribes a multitude of tRNA and 5S rRNA genes as well as other small RNA genes distributed through the genome. By being sequence-specific, precise and efficient, transcription termination by pol III not only defines the 3′ end of the nascent RNA which directs subsequent association with the stabilizing La protein, it also prevents transcription into downstream DNA and promotes efficient recycling. Each of the RNA polymerases appears to have evolved unique mechanisms to initiate the process of termination in response to different types of termination signals. However, in eukaryotes much less is known about the final stage of termination, destabilization of the elongation complex with release of the RNA and DNA from the polymerase active center. By comparison to pols I & II, pol III exhibits the most direct coupling of the initial and final stages of termination, both of which occur at a short oligo(dT) tract on the non-template strand (dA on the template) of the DNA. While pol III termination is autonomous involving the core subunits C2 and probably C1, it also involves subunits C11, C37 and C53, which act on the pol III catalytic center and exhibit homology to the pol II elongation factor TFIIS, and TFIIFα/β respectively. Here we compile knowledge of pol III termination and associate mutations that affect this process with structural elements of the polymerase that illustrate the importance of C53/37 both at its docking site on the pol III lobe and in the active center. The models suggest that some of these features may apply to the other eukaryotic pols.
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