THE CLONED RNA POLYMERASE-II TRANSCRIPTION FACTOR-IID SELECTS RNA POLYMERASE-III TO TRANSCRIBE THE HUMAN U6 GENE INVITRO
THE CLONED RNA POLYMERASE-II TRANSCRIPTION FACTOR-IID SELECTS RNA POLYMERASE-III TO TRANSCRIBE THE HUMAN U6 GENE INVITRO
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DOI：
10.1101/gad.5.8.1477
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发表时间：
1991-08-01
影响因子：
10.5
通讯作者：
HERNANDEZ, N
中科院分区：
文献类型：
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作者：
LOBO, SM;LISTER, J;HERNANDEZ, N
尽管人类U2和U6 snRNA基因由不同的RNA聚合酶（即分别为RNA聚合酶II和III）转录，但它们的启动子在结构上非常相似。两者都含有近端序列元件（PSE）和含有八聚体基序的增强子，并且这些元件在两个启动子之间可以互换。 U6 启动子的 RNA 聚合酶 III 特异性是由位于 25 位周围的单个富含 A/T 的元件赋予的。 A/T 富含区域的突变将 U6 启动子转化为 RNA 聚合酶 II 启动子，而 A/T 富含区域插入 U2 启动子则将该启动子转化为 RNA 聚合酶 III 启动子。我们表明，这种富含 A/T 的元件可以被许多源自 RNA 聚合酶 11 转录的 mRNA 启动子的 TATA 盒取代，对 RNA 聚合酶 III 转录影响很小。此外，克隆的RNA聚合酶11转录因子TFIID既结合U6 A/T富含区又在体外指导准确的RNA聚合酶III转录。 U6 A/T 富含区域的突变将 U6 启动子转化为 RNA 聚合酶 11 启动子，也消除了 TFIID 结合。总之，这些观察结果表明，与mRNA启动子不同，在人snRNA启动子中，TFIID的结合指导RNA聚合酶III转录复合物的组装，而TFIID结合的缺乏导致RNA聚合酶11 snRNA转录复合物的组装。
Although the human U2 and U6 snRNA genes are transcribed by different RNA polymerases (i.e., RNA polymerases II and III, respectively), their promoters are very similar in structure. Both contain a proximal sequence element (PSE) and an octamer motif-containing enhancer, and these elements are interchangeable between the two promoters. The RNA polymerase III specificity of the U6 promoter is conferred by a single A/T-rich element located around position-25. Mutation of the A/T-rich region converts the U6 promoter into an RNA polymerase II promoter, whereas insertion of the A/T-rich region into the U2 promoter converts that promoter into an RNA polymerase III promoter. We show that this A/T-rich element can be replaced by a number of TATA boxes derived from mRNA promoters transcribed by RNA polymerase 11 with little effect on RNA polymerase III transcription. Furthermore, the cloned RNA polymerase 11 transcription factor TFIID both binds to the U6 A/T-rich region and directs accurate RNA polymerase Ill transcription in vitro. Mutations in the U6 A/T-rich region that convert the U6 promoter into an RNA polymerase 11 promoter also abolish TFIID binding. Together, these observations suggest that in the human snRNA promoters, unlike in mRNA promoters, binding of TFIID directs the assembly of RNA polymerase Ill transcription complexes, whereas the lack of TFIID binding results in the assembly of RNA polymerase 11 snRNA transcription complexes.