High-resolution structural analysis of chromatin at specific loci: Saccharomyces cerevisiae silent mating-type locus HMRa.
High-resolution structural analysis of chromatin at specific loci: Saccharomyces cerevisiae silent mating-type locus HMRa.
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特定位点染色质的高分辨率结构分析：酿酒酵母沉默交配型位点 HMRa。
DOI：
10.1128/mcb.19.12.7944
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发表时间：
1999
影响因子：
5.3
通讯作者：
Simpson,RT
中科院分区：
文献类型：
--
作者：
Ravindra,A;Weiss,K;Simpson,RT
遗传和生化证据表明染色质结构与酵母 III 号染色体端粒附近两个静止交配型基因座的沉默有关。通过高分辨率微球菌核酸酶图谱，我们表明 HMRa 基因座具有 12 个精确定位的核小体，跨越 E 和 I 消音器元件之间的距离。核小体通过非常短的连接体成对排列；这些对通过~20 bp 的较长连接体彼此分开。组蛋白 H4 的基本氨基末端区域和沉默信息调节蛋白 Sir3p 对于沉默位点的有组织的抑制性染色质结构都是必需的。与 HMRa 相比，活性 MATa 基因座盒中的启动子在 TATA 盒的可用性方面仅存在很小的差异。与之前研究的 HMLα 基因座相比，该沉默基因座的染色质结构特征表明沉默机制存在差异，并且可能与交配型互变期间的供体选择有关。
Genetic and biochemical evidence implicates chromatin structure in the silencing of the two quiescent mating-type loci near the telomeres of chromosome III in yeast. With high-resolution micrococcal nuclease mapping, we show that theHMRa locus has 12 precisely positioned nucleosomes spanning the distance between the E and I silencer elements. The nucleosomes are arranged in pairs with very short linkers; the pairs are separated from one another by longer linkers of ∼20 bp. Both the basic amino-terminal region of histone H4 and the silent information regulator protein Sir3p are necessary for the organized repressive chromatin structure of the silent locus. Compared toHMRa, only small differences in the availability of the TATA box are present for the promoter in the cassette at the activeMATa locus. Features of the chromatin structure of this silent locus compared to the previously studiedHMLα locus suggest differences in the mechanisms of silencing and may relate to donor selection during mating-type interconversion.