The requirements for COMPASS and Paf1 in transcriptional silencing and methylation of histone H3 in Saccharomyces cerevisiae
The requirements for COMPASS and Paf1 in transcriptional silencing and methylation of histone H3 in Saccharomyces cerevisiae
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DOI：
10.1534/genetics.106.055400
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发表时间：
2006-06-01
期刊：
影响因子：
3.3
通讯作者：
Bryk, Mary
中科院分区：
文献类型：
--
作者：
Mueller, John E.;Canze, Megan;Bryk, Mary
含有Set 1的复合物COMPASS在酿酒酵母中甲基化赖氨酸4（K4）上的组蛋白H3。尽管K4-三甲基化H3与RNA聚合酶II转录的基因组区域优先相关，但转录沉默是S.在酿酒酵母中，组蛋白甲基化缺陷对基因表达有明显的影响。为了更好地理解COMPASS在转录沉默中的作用，我们使用北方分析确定了COMPASS的哪些成员是核糖体DNA位点（rDNA）、端粒和沉默交配位点（HM）沉默所需的。我们的研究结果表明，COMPASS的大多数成员需要在rDNA和端粒沉默，而没有需要在HM基因座的内源基因沉默。为了补充基因表达分析，进行定量蛋白质印迹实验以确定组蛋白H3甲基化所需的COMPASS成员。虽然大多数是三甲基化所必需的，但缺乏某些COMPASS蛋白的细胞保持K4单甲基化和二甲基化H3水平降低，这表明一些COMPASS成员具有冗余功能。最后，我们发现Paf 1是沉默所必需的，并且在rDNA上K4-甲基化H3，这表明K4-甲基化H3在基因沉默中可能起直接作用。
The Set1-containing complex, COMPASS, methylates histone H3 on lysine 4 (K4) in Saccharomyces carevisiae. Despite the preferential association of K4-trimethylated H3 with regions of the genome that are transcribed by RNA polymerase II, transcriptional silencing is one of the few cases in S. cerevisiae where histone-methylation defects have a clear effect on gene expression. To better understand the role of COMPASS in transcriptional silencing, we have determined which members of COMPASS are required for silencing at the ribosomal DNA locus (rDNA), a telomere, and the silent mating loci (HM) using Northern analyses. Our findings indicate that most members of COMPASS are required for silencing at the rDNA and telomere, while none are required for silencing of endogenous genes at the HM loci. To complement gene-expression analysis, quantitative Western blot experiments were performed to determine the members of COMPASS that are required for methylation of histone H3. While most are required for trimethylation, cells lacking certain COMPASS proteins maintain reduced levels of K4 mono- and dimethylated H3, suggesting that some COMPASS members have redundant function. Finally, we show Paf1 is required for silencing and K4-methylated H3 at the rDNA, Suggesting a possible direct role for K4-methylated H3 in gene silencing.