Briggs S D, Bryk M, Strahl B D, Cheung W L, Davie J K, Dent S Y, Winston F, Allis C D
Department of Biochemistry and Molecular Genetics, University of Virginia Health System, Charlottesville, Virginia 22908, USA.
Genes Dev. 2001 Dec 15;15(24):3286-95. doi: 10.1101/gad.940201.
Histone methylation is known to be associated with both transcriptionally active and repressive chromatin states. Recent studies have identified SET domain-containing proteins such as SUV39H1 and Clr4 as mediators of H3 lysine 9 (Lys9) methylation and heterochromatin formation. Interestingly, H3 Lys9 methylation is not observed from bulk histones isolated from asynchronous populations of Saccharomyces cerevisiae or Tetrahymena thermophila. In contrast, H3 lysine 4 (Lys4) methylation is a predominant modification in these smaller eukaryotes. To identify the responsible methyltransferase(s) and to gain insight into the function of H3 Lys4 methylation, we have developed a histone H3 Lys4 methyl-specific antiserum. With this antiserum, we show that deletion of SET1, but not of other putative SET domain-containing genes, in S. cerevisiae, results in the complete abolishment of H3 Lys4 methylation in vivo. Furthermore, loss of H3 Lys4 methylation in a set1 Delta strain can be rescued by SET1. Analysis of histone H3 mutations at Lys4 revealed a slow-growth defect similar to a set1 Delta strain. Chromatin immunoprecipitation assays show that H3 Lys4 methylation is present at the rDNA locus and that Set1-mediated H3 Lys4 methylation is required for repression of RNA polymerase II transcription within rDNA. Taken together, these data suggest that Set1-mediated H3 Lys4 methylation is required for normal cell growth and transcriptional silencing.
已知组蛋白甲基化与转录活性和抑制性染色质状态均相关。最近的研究已确定含SET结构域的蛋白，如SUV39H1和Clr4，是H3赖氨酸9（Lys9）甲基化和异染色质形成的介质。有趣的是，从酿酒酵母或嗜热四膜虫的异步群体中分离出的大量组蛋白中未观察到H3 Lys9甲基化。相反，H3赖氨酸4（Lys4）甲基化是这些较小真核生物中的主要修饰。为了鉴定负责的甲基转移酶并深入了解H3 Lys4甲基化的功能，我们开发了一种组蛋白H3 Lys4甲基特异性抗血清。利用这种抗血清，我们发现酿酒酵母中SET1的缺失而非其他假定的含SET结构域基因的缺失，导致体内H3 Lys4甲基化完全消失。此外，set1Δ菌株中H3 Lys4甲基化的缺失可以被SET1挽救。对赖氨酸4处组蛋白H3突变的分析揭示了一种类似于set1Δ菌株的生长缓慢缺陷。染色质免疫沉淀分析表明，H3 Lys4甲基化存在于rDNA基因座，并且Set1介导的H3 Lys4甲基化是rDNA内RNA聚合酶II转录抑制所必需的。综上所述，这些数据表明Set1介导的H3 Lys4甲基化是正常细胞生长和转录沉默所必需的。
