High-resolution structural analysis of chromatin at specific loci: Saccharomyces cerevisiae silent mating type locus HMLalpha.
High-resolution structural analysis of chromatin at specific loci: Saccharomyces cerevisiae silent mating type locus HMLalpha.
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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 HMLalpha。
DOI：
10.1128/mcb.18.9.5392
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发表时间：
1998
影响因子：
5.3
通讯作者：
Simpson,RT
中科院分区：
文献类型：
--
作者：
Weiss,K;Simpson,RT
遗传学研究表明，染色质结构参与了酿酒酵母沉默交配型基因座的抑制。转录沉默 HMLα 和活性 MATα 的核苷酸分辨率染色质图谱表明，独特的组织染色质结构表征了 HMLα 的沉默状态。精确定位的核小体毗邻沉默子，延伸至 α1 和 α2 编码区。 HO 核酸内切酶识别位点（MATα 处的核酸酶过敏）在 HMLα 处受到保护。尽管两个精确定位的核小体在 HMLα 处整合了转录起始位点，但 α1 和 α2 基因的启动子区域不含核小体，并且在抑制位点中比在转录位点中对核酸酶更敏感。 HML 沉默所必需的基因突变会破坏 HML-I 附近的核小体阵列，但不会破坏 HML-E 附近的核小体阵列，因为 HML-E 更接近第三号染色体的端粒。在启动子和HO位点，Sir蛋白和组蛋白H4 N端缺失突变体中的HMLα结构与转录活性MATα的结构相同。 HMLα 的不连续染色质结构与在抑制的 a 细胞特异性基因和重组增强子中发现的连续核小体结构形成对比。 HMLα 的标点符号对于高阶结构或核骨架相互作用可能是必要的。 HMLα 独特的染色质结构可能与转录抑制和重组能力的综合要求有关。
Genetic studies have suggested that chromatin structure is involved in repression of the silent mating type loci inSaccharomyces cerevisiae. Chromatin mapping at nucleotide resolution of the transcriptionally silentHMLα and the activeMATα shows that unique organized chromatin structure characterizes the silent state ofHMLα. Precisely positioned nucleosomes abutting the silencers extend over the α1 and α2 coding regions. The HO endonuclease recognition site, nuclease hypersensitive atMATα, is protected atHMLα. Although two precisely positioned nucleosomes incorporate transcription start sites atHMLα, the promoter region of the α1 and α2 genes is nucleosome free and more nuclease sensitive in the repressed than in the transcribed locus. Mutations in genes essential forHMLsilencing disrupt the nucleosome array near HML-I but not in the vicinity of HML-E, which is closer to the telomere of chromosome III. At the promoter and the HO site, the structure ofHMLα in Sir protein and histone H4 N-terminal deletion mutants is identical to that of the transcriptionally activeMATα. The discontinuous chromatin structure ofHMLα contrasts with the continuous array of nucleosomes found at repressed a-cell-specific genes and the recombination enhancer. Punctuation atHMLα may be necessary for higher-order structure or karyoskeleton interactions. The unique chromatin architecture ofHMLα may relate to the combined requirements of transcriptional repression and recombinational competence.