Johnson S P, Warner J R
Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York 10461.
Mol Cell Biol. 1989 Nov;9(11):4986-93. doi: 10.1128/mcb.9.11.4986-4993.1989.
The rRNA genes in most eucaryotic organisms are present in a tandem array. There is substantial evidence that transcription of one of these genes may not be independent of transcription of others. In particular, in the yeast Saccharomyces cerevisiae, the enhancer of rRNA transcription that lies 2.2 kilobases 5' of the transcription initiation site is at least partly within the upstream transcription unit. To ask more directly about the relationship of the tandemness of these genes to their transcription, we have constructed a minirepeat containing two identifiable test genes, with or without enhancer(s). On integration into the URA3 locus, these genes were transcribed by RNA polymerase I. A single enhancer effectively stimulated transcription of both genes by 10- to 30-fold, even when it was located upstream of both or downstream of both. Two enhancers had roughly additive effects. These results suggest a model of enhancer function in tandemly repeated genes.
大多数真核生物中的核糖体RNA（rRNA）基因以串联阵列的形式存在。有大量证据表明，这些基因中的一个基因的转录可能并非独立于其他基因的转录。特别是在酿酒酵母中，位于转录起始位点上游2.2千碱基处的rRNA转录增强子至少部分位于上游转录单元内。为了更直接地探究这些基因的串联性与其转录之间的关系，我们构建了一个包含两个可识别测试基因的小重复序列，有或没有增强子。整合到URA3位点后，这些基因由RNA聚合酶I转录。即使单个增强子位于两个基因的上游或下游，它也能有效地将两个基因的转录刺激10至30倍。两个增强子具有大致相加的效应。这些结果提示了串联重复基因中增强子功能的一种模型。
