A DNA minor groove-binding ligand both potentiates and arrests transcription by RNA polymerase II. Elongation factor SII enables readthrough at arrest sites.
A DNA minor groove-binding ligand both potentiates and arrests transcription by RNA polymerase II. Elongation factor SII enables readthrough at arrest sites.
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DOI：
10.1006/jmbi.1994.1185
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发表时间：
1994-02
影响因子：
5.6
通讯作者：
J. Mote;Pejman Ghanouni;D. Reines
中科院分区：
文献类型：
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作者：
J. Mote;Pejman Ghanouni;D. Reines
RNA聚合酶II在体内和体外都遇到转录延长的各种障碍。这些包括DNA序列元件和与DNA大沟结合的蛋白质。延伸因子SII与RNA聚合酶II结合，使酶能够绕过这些障碍。SII还通过转录延长复合物激活新生RNA切割，这是一种密切参与通读过程的活性。在这里，我们确定了另一种类型的可逆阻断RNA聚合酶II转录，抗肿瘤抗生素偏端霉素，它结合在小沟的A + T丰富的DNA。SII促进了由药物的DNA结合引起的阻滞位点的通读。响应于SII，这些复合物切割它们的新生RNA链。这些发现证实，SII是一个通用的延伸因子，通过各种障碍增强转录。它们还强化了SII通过激活新生RNA切割来刺激转录的观点。在某些情况下，偏端霉素可以通过天然存在的暂停位点增强转录。我们还表明，在偏端霉素的存在下，模板经历了构象变化。这表明，偏端霉素可以将DNA从一个延长非许可的配置到一个延长许可的形式，我们把这作为独立的证据，证实DNA结构影响RNA聚合酶II的转录延伸。
RNA polymerase II encounters various obstacles to transcript elongation both in vivo and in vitro. These include DNA sequence elements and protein bound to the major groove of DNA. Elongation factor SII binds to RNA polymerase II and enables the enzyme to bypass these impediments. SII also activates nascent RNA cleavage by the arrested transcription elongation complex, an activity intimately involved in the readthrough process. Here we identify another type of reversible blockage to RNA polymerase II transcription, the antitumor antibiotic distamycin, which binds in the minor groove of A + T-rich DNA. SII facilitates readthrough of arrest sites resulting from DNA-binding of the drug. In response to SII, these complexes cleave their nascent RNA chains. These findings confirm that SII is a general elongation factor that potentiates transcription through a variety of impediments. They also strengthen the idea that SII stimulates transcription by activating nascent RNA cleavage. In some cases, distamycin can potentiate transcription through a naturally occurring pause site. We also show that the template undergoes a conformational change in the presence of distamycin. This suggests that distamycin can transform DNA from an elongation-non-permissive configuration into an elongation-permissive form and we take this as independent evidence confirming that DNA structure influences transcription elongation by RNA polymerase II.