ARCHITECTURE OF A YEAST U6 RNA GENE PROMOTER
ARCHITECTURE OF A YEAST U6 RNA GENE PROMOTER
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DOI：
10.1128/mcb.13.5.3015
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发表时间：
1993-05-01
影响因子：
5.3
通讯作者：
BROW, DA
中科院分区：
文献类型：
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作者：
ESCHENLAUER, JB;KAISER, MW;BROW, DA
脊椎动物和酵母U6小核RNA基因的启动子在结构上不同，尽管两者都被RNA聚合酶III识别。脊椎动物U6 RNA基因只有上游启动子，而酵母U6 RNA基因(SNR6)的内部和下游启动子元件分别与tRNA基因内的A-和B-块元件匹配。SNR6 A或B区块的替代极大地减少了U6 RNA在体内的积累，而能够转录RNA聚合酶III的亚细胞提取物在SNR6下游B区块和tRNA基因内B区块上产生了几乎相同的DNase I保护模式。我们得出结论，SNR6启动子在功能上类似于tRNA基因启动子，尽管基因外缺失突变的影响表明SNR6 B区块的下游位置对其功能施加了独特的位置限制。脊椎动物和酵母的U6 RNA基因都有tRNA基因中没有的上游TATA盒元件。SNR6TATA盒的替换改变了体内转录起始位置，而更上游的序列替换对SNR6转录没有影响。我们提出了一个SNR6转录复合体的模型，从它们对转录起始因子TFIIIB结合的影响来解释这些结果。
The promoters of vertebrate and yeast U6 small nuclear RNA genes are structurally dissimilar, although both are recognized by RNA Polymerase III. Vertebrate U6 RNA genes have exclusively upstream promoters, while the U6 RNA gene from the yeast Saccharomyces cerevisiae (SNR6) has internal and downstream promoter elements that match the tRNA gene intragenic A- and B-block elements, respectively. Substitution of the SNR6 A or B block greatly diminished U6 RNA accumulation in vivo, and a subcellular extract competent for RNA polymerase III transcription generated nearly identical DNase I protection patterns over the SNR6 downstream B block and a tRNA gene intragenic B block. We conclude that the SNR6 promoter is functionally similar to tRNA gene promoters, although the effects of extragenic deletion mutations suggest that the downstream location of the SNR6 B block imposes unique positional constraints on its function. Both vertebrate and yeast U6 RNA genes have an upstream TATA box element not normally found in tRNA genes. Substitution of the SNR6 TATA box altered the site of transcription initiation in vivo, while substitution of sequences further upstream had no effect on SNR6 transcription. We present a model for the SNR6 transcription complex that explains these results in terms of their effects on the binding of transcription initiation factor TFIIIB.