Multiple functional enhancer motifs of rat ribosomal gene.
Multiple functional enhancer motifs of rat ribosomal gene.
复制标题
大鼠核糖体基因的多个功能增强子基序。
DOI：
10.1007/bf00229815
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发表时间：
1991
影响因子：
4.3
通讯作者：
Book,CB
中科院分区：
文献类型：
--
作者：
Jacob,ST;Zhang,J;Garg,LC;Book,CB
本实验室以前的研究已经确定了174的增强子元件，该元件位于起始点上游2kb。一半的增强子作用由174 by区3‘端的37 by元件控制。我们现在报告，位于37by元件上游的43by相邻结构域构成了rDNA增强子的另一个基序。当rDNA核心启动子上游的43位DNA组成的质粒在分级的大鼠肿瘤细胞提取物(组分DE-B)中转录时，rDNA的转录增加了4倍。凝胶迁移率改变和DNAase I足迹分析表明，增强子结合蛋白(E1BF)纯化的37不仅与增强子基序E1相互作用，而且通过增强子结构域E2与邻近的43相互作用。在迁移率改变分析中，通过与未标记的37个DNA和43个片段的竞争以及与非特异性DNA的不竞争来证明该结合的特异性。这些研究表明，单个PolI转录因子可以与多个增强子结构域结合，而没有明显的序列同源性，这种多重相互作用可能导致核糖体基因从核心启动子最大限度地转录。
Previous studies from this laboratory have characterized a 174 by enhancer element which is located 2kb upstream of the initiation site. Half of the enhancer action is controlled by a 37 by element at the 3′ end of the 174 by region. We now report that a 43 by adjacent domain which is located upstream of the 37 by element constitutes an additional motif of the rDNA enhancer. When the plasmid consisting of the 43 by DNA upstream of the rDNA core promoter was transcribed in a fractionated rat tumor cell extract (fraction DE-B), transcription of rDNA was augmented 4 fold. Electrophoretic mobility shift and DNAase I footprinting analyses showed that the purified 37 by enhancer (E1)-binding protein, (E1BF) not only interacted with the enhancer motif El but also interacted with the neighbouring 43 by enhancer domain E2. The specificity of the binding was demonstrated by competition with unlabeled 37 by and 43 by fragment and lack of competition with nonspecific DNAs in the mobility shift assay. These studies have shown that a single pol I transcription factor can bind to multiple enhancer domains with no significant sequence homologies and such multiple interactions may result in maximal transcription of ribosomal gene from the core promoter.