An unusual form of transcriptional silencing in yeast ribosomal DNA
An unusual form of transcriptional silencing in yeast ribosomal DNA
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DOI：
10.1101/gad.11.2.241
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发表时间：
1997-01-15
影响因子：
10.5
通讯作者：
Boeke, JD
中科院分区：
文献类型：
--
作者：
Smith, JS;Boeke, JD
酿酒酵母染色体大区域的普遍转录抑制发生在沉默交配位点和端粒，并由沉默信息调节因子（SIR）基因介导。我们在S.在核糖体DNA（rDNA）串联阵列中的酿酒酵母。Ty 1反转录转座子标记的弱化的URA 3基因（Ty 1-mURA 3）有效地整合到rDNA。rDNA中的mURA 3标记以SIR 2依赖的方式被转录沉默。MET 15和LEU 2也部分沉默，表明rDNA沉默可能是相当普遍的。SIR 4的缺失增强了mURA 3和MET 15的沉默，但SIR 1或SIR 3的缺失不影响沉默，表明沉默机制不同于端粒和沉默交配位点。SIR 2的缺失导致在体内的rDNA的peptien交联增加，这表明rDNA中的特定染色质结构下调聚合酶II启动子。
Generalized transcriptional repression of large chromosomal regions in Saccharomyces cerevisiae occurs at the silent mating loci and at telomeres and is mediated by the silent information regulator (SIR) genes. We have identified a novel form of transcriptional silencing in S. cerevisiae in the ribosomal DNA (rDNA) tandem array. Ty1 retrotransposons marked with a weakened URA3 gene (Ty1-mURA3) efficiently integrated into rDNA. The mURA3 marker in rDNA was transcriptionally silenced in a SIR2-dependent manner. MET15 and LEU2 were also partially silenced, indicating that rDNA silencing may be quite general. Deletion of SIR4 enhanced mURA3 and MET15 silencing, but deletion of SIR1 or SIR3 did not affect silencing, indicating that the mechanism of silencing differs from that at telomeres and silent mating loci. Deletion of SIR2 resulted in increased psoralen cross-linking of the rDNA in vivo, suggesting that a specific chromatin structure in rDNA down-regulates polymerase II promoters.