Telomere looping permits gene activation by a downstream UAS in yeast
Telomere looping permits gene activation by a downstream UAS in yeast
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DOI：
10.1038/35051119
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发表时间：
2001-01-04
期刊：
影响因子：
64.8
通讯作者：
Ptashne, M
中科院分区：
文献类型：
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作者：
de Bruin, D;Zaman, Z;Ptashne, M
在酵母（酿酒酵母）中，转录激活因子，如Gal 4和Gal 4-VP 16，通常从位于转录起始位点上游约250个碱基对的上游激活序列（UAS）中的位点起作用（1）。然而，与它们在哺乳动物细胞中的行为相反，当位于基因上游（2）或下游（3，4）的任何地方大于600-700个碱基对的距离时，这种激活剂不能起作用。在这里，我们表明，在酵母中，一个基因携带的增强子定位1-2个酶的基因下游被激活，如果报告连接到端粒，但如果它是位于内部染色体位点。这些观察结果可以通过发现酵母端粒形成回折或环状结构来解释。由于酵母端粒区类似于高等真核生物中发现的异染色质，这些发现也可以解释为什么一些高等真核生物基因的转录取决于它们在异染色质中的位置。
In yeast (Saccharomyces cerevisiae), transcriptional activators, such as Gal4 and Gal4-VP16, work ordinarily from sites located in the upstream activating sequence (UAS) positioned about 250 base pairs upstream of the transcription start site(1). In contrast to their behaviour in mammalian cells, however, such activators fail to work when positioned at distances greater than similar to 600-700 base pairs upstream(2), or anywhere downstream(3,4) of the gene. Here we show that, in yeast, a gene bearing an enhancer positioned 1-2 kilobases downstream of the gene is activated if the reporter is linked to a telomere, but not if it is positioned at an internal chromosomal locus. These observations are explained by the finding that yeast telomeres form back-folding, or looped, structures. Because yeast telomeric regions resemble the heterochromatin found in higher eukaryotes, these findings might also explain why transcription of some higher eukaryotic genes depends on their location in heterochromatin.