Kleinert H, Assert R, Benecke B J
Department of Biochemistry, Faculty of Chemistry, Ruhr-University, Bochum, Federal Republic of Germany.
J Biol Chem. 1991 Dec 15;266(35):23872-7.
Octamer sequence elements were analyzed for their capacity to induce the 7S K "core" promoter in vivo. The U6 distal sequence element (DSE) which contains a consensus sequence octamer, was able to support efficient 7S K expression in vivo. In contrast, no such function could be attributed to the octamer-like element alone, which is present within the 7S K DSE. However, conversion of this octamer-like element (ATTTaGCAT) to the octamer consensus sequence ATTTGCAT generated a potent DSE, even in the absence of the CACCC box, which constitutes the major functional element of the 7S K DSE. Both the consensus and the octamer-like sequences revealed no cooperativity with the CACCC box. Together, these results demonstrate that the octamer-like element of the wild-type 7S K DSE is definitely not functional in vivo. Furthermore, our experiments indicate that in contrast to the RNA polymerase II-transcribed small nuclear RNA genes, in intact cells a single functional DSE motif is necessary and sufficient for maximal transcription by RNA polymerase III of the 7S K RNA gene.
分析八聚体序列元件在体内诱导7SK“核心”启动子的能力。包含共有序列八聚体的U6远端序列元件（DSE）能够在体内支持高效的7SK表达。相比之下，单独存在于7SK DSE内的类似八聚体元件没有这种功能。然而，即使在没有构成7SK DSE主要功能元件的CACCC框的情况下，将这种类似八聚体元件（ATTTaGCAT）转换为八聚体共有序列ATTTGCAT也会产生一个有效的DSE。共有序列和类似八聚体序列都未显示与CACCC框有协同作用。总之，这些结果表明野生型7SK DSE的类似八聚体元件在体内绝对没有功能。此外，我们的实验表明，与RNA聚合酶II转录的小核RNA基因不同，在完整细胞中，单个功能性DSE基序对于RNA聚合酶III转录7SK RNA基因实现最大转录是必要且充分的。
