The Bur1 cyclin-dependent protein kinase is required for the normal pattern of histone methylation by Set2
The Bur1 cyclin-dependent protein kinase is required for the normal pattern of histone methylation by Set2
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DOI：
10.1128/mcb.26.8.3029-3038.2006
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发表时间：
2006-04-01
影响因子：
5.3
通讯作者：
Prelich, G
中科院分区：
文献类型：
--
作者：
Chu, YY;Sutton, A;Prelich, G
BUR1 和 BUR2 编码细胞周期蛋白依赖性蛋白激酶复合物的催化和调节亚基，该复合物对于正常生长至关重要，并且在转录延伸中具有一般作用。为了深入了解其在体内的具体作用，我们发现了可以逆转 bur1 Delta 细胞严重生长缺陷的突变。这一选择鉴定了 SET2 中的突变，SET2 编码一种靶向组蛋白 H3 赖氨酸 36 的组蛋白甲基化酶，并且与 BUR1 一样，在转录延伸过程中的作用尚不清楚。这种遗传关系表明 SET2 活性是 bur1 Delta 菌株中观察到的生长缺陷所必需的。这种 SET2 依赖性生长抑制是通过组蛋白 H3 在赖氨酸 36 上的甲基化发生的，因为 SET2 的甲基化缺陷等位基因或组蛋白 H3 K36R 突变也会抑制 bur1 Delta。我们在生化水平上探讨了BUR1和SET2之间的关系，发现在野生型细胞中组蛋白H3在第36位赖氨酸上发生单甲基化、二甲基化和三甲基化，但在bur1和bur2突变株中三甲基化显着减少。在 RNA 聚合酶 II C 端结构域截短突变体和 spt16 突变株中观察到类似的甲基化模式。染色质免疫沉淀测定表明，在 bur2 Delta 菌株中，开放阅读框上三甲基化 K36 的转录依赖性增加显着减少。这些结果建立了调节蛋白激酶和组蛋白甲基化之间的联系，并产生了一个模型，其中 Bur1-Bur2 复合物抵消了 Set2 依赖性组蛋白甲基化的抑制作用。
BUR1 and BUR2 encode the catalytic and regulatory subunits of a cyclin-dependent protein kinase complex that is essential for normal growth and has a general role in transcription elongation. To gain insight into its specific role in vivo, we identified mutations that reverse the severe growth defect of bur1 Delta cells. This selection identified mutations in SET2, which encodes a histone methylase that targets lysine 36 of histone H3 and, like BUR1, has a poorly characterized role during transcription elongation. This genetic relationship indicates that SET2 activity is required for the growth defect observed in bur1 Delta strains. This SET2-dependent growth inhibition occurs via methylation of histone H3 on lysine 36, since a methylation-defective allele of SET2 or a histone H3 K36R mutation also suppressed bur1 Delta. We have explored the relationship between BUR1 and SET2 at the biochemical level and find that histone H3 is monomethylated, dimethylated, and trimethylated on lysine 36 in wild-type cells, but trimethylation is significantly reduced in bur1 and bur2 mutant strains. A similar methylation pattern is observed in RNA polymerase II C-terminal domain truncation mutants and in an spt16 mutant strain. Chromatin immunoprecipitation assays reveal that the transcription-dependent increase in trimethylated K36 over open reading frames is significantly reduced in bur2 Delta strains. These results establish links between a regulatory protein kinase and histone methylation and lead to a model in which the Bur1-Bur2 complex counteracts an inhibitory effect of Set2-dependent histone methylation.