Evidence for silencing compartments within the yeast nucleus: A role for telomere proximity and SIR protein concentration in silencer-mediated repression
Evidence for silencing compartments within the yeast nucleus: A role for telomere proximity and SIR protein concentration in silencer-mediated repression
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DOI：
10.1101/gad.10.14.1796
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发表时间：
1996-07-15
影响因子：
10.5
通讯作者：
Gasser, SM
中科院分区：
文献类型：
--
作者：
Maillet, L;Boscheron, C;Gasser, SM
酵母中沉默交配型基因座的转录抑制需要通过在顺式作用沉默元件处形成的特异性相互作用来靶向沉默信息调节器（Sir）蛋白。我们在这里表明，一个报告基因两侧的两个功能沉默不被抑制时，整合在>200 kb的端粒。通过从整合的报告基因产生新的端粒13 kb或通过SIR 1、SIR 3和/或SIR 4的表达升高来恢复抑制。偶联表达抑制在一个加性的方式，这表明，所有三个因素都在限制浓度。当过表达时，Sir 3和Sir 4分散在整个核质中，与野生型细胞相反，它们与端粒一起聚集在有限数量的病灶中。因此，有效的沉默功能似乎需要接近一个集中的爵士蛋白池，即接近端粒，或离域的沉默因子。
Transcriptional repression at the silent mating-type loci in yeast requires the targeting of silent information regulator (Sir) proteins through specific interactions formed at cis-acting silencer elements. We show here that a reporter gene flanked by two functional silencers is not repressed when integrated at >200 kb from a telomere. Repression is restored by creation of a new telomere 13 kb from the integrated reporter or by elevated expression of SIR1, SIR3, and/or SIR4. Coupled expression represses in an additive manner, suggesting that all three factors are in limiting concentrations. When overexpressed, Sir3 and Sir4 are dispersed throughout the nucleoplasm, in contrast to wild-type cells where they are clustered in a limited number of foci together with telomeres. Efficient silencer function thus seems to require either proximity to a pool of concentrated Sir proteins, that is, proximity to telomeres, or delocalization of the silencing factors.