Clustering heterochromatin: Sir3 promotes telomere clustering independently of silencing in yeast.
Clustering heterochromatin: Sir3 promotes telomere clustering independently of silencing in yeast.
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DOI：
10.1083/jcb.201008007
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发表时间：
2011-02-07
期刊：
影响因子：
--
通讯作者：
Taddei A
中科院分区：
文献类型：
--
作者：
Ruault M;De Meyer A;Loïodice I;Taddei A
端粒上的Sir 3结合位点阵列足以促进长距离的端粒间相互作用。细胞核的一般特征是重复脱氧核糖核酸序列以聚集沉默因子的簇的形式组织。在芽殖酵母中，我们研究了端粒如何在与沉默复合物Sir 2-Sir 3-Sir 4相关的核周灶中聚集，并发现Sir 3限制端粒聚集。Sir 3过表达触发端粒灶分组为更大的灶，重新定位到核内部，并与更稳定的沉默在亚端粒区域。此外，我们发现Sir 3介导端粒聚集的能力可以与其在沉默中的作用分开。事实上，nonacetylable Sir 3，这是无法传播到亚端粒区域，可以介导端粒聚类独立的Sir 2-Sir 4，只要它是针对端粒的Rap 1蛋白。因此，在端粒的Sir 3结合位点的阵列出现作为促进端粒之间的反式相互作用的唯一要求。我们提出，类似的机制，涉及蛋白质能够寡聚占长程相互作用，影响许多生物体中的基因组功能。
Arrays of Sir3 binding sites at telomeres are sufficient to promote long-range trans-telomere interactions. A general feature of the nucleus is the organization of repetitive deoxyribonucleic acid sequences in clusters concentrating silencing factors. In budding yeast, we investigated how telomeres cluster in perinuclear foci associated with the silencing complex Sir2–Sir3–Sir4 and found that Sir3 is limiting for telomere clustering. Sir3 overexpression triggers the grouping of telomeric foci into larger foci that relocalize to the nuclear interior and correlate with more stable silencing in subtelomeric regions. Furthermore, we show that Sir3′s ability to mediate telomere clustering can be separated from its role in silencing. Indeed, nonacetylable Sir3, which is unable to spread into subtelomeric regions, can mediate telomere clustering independently of Sir2–Sir4 as long as it is targeted to telomeres by the Rap1 protein. Thus, arrays of Sir3 binding sites at telomeres appeared as the sole requirement to promote trans-interactions between telomeres. We propose that similar mechanisms involving proteins able to oligomerize account for long-range interactions that impact genomic functions in many organisms.
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