Histone H2B monoubiquitylation (H2Bub1) is tightly linked to RNA polymerase II transcription elongation, and is also directly implicated in DNA replication and repair. Loss of H2Bub1 is associated with defects in cell cycle progression, but how these are related to its various functions, and the underlying mechanisms involved, is not understood. Here we describe a role for H2Bub1 in the regulation of replication-dependent histone genes in the fission yeast Schizosaccharomyces pombe. H2Bub1 activates histone genes indirectly by suppressing antisense transcription of ams2+-a gene encoding a GATA-type transcription factor that activates histone genes and is required for assembly of centromeric chromatin. Mutants lacking the ubiquitylation site in H2B or the H2B-specific E3 ubiquitin ligase Brl2 had elevated levels of ams2+ antisense transcripts and reduced Ams2 protein levels. These defects were reversed upon inhibition of Cdk9-an ortholog of the kinase component of positive transcription elongation factor b (P-TEFb)-indicating that they likely resulted from aberrant transcription elongation. Reduced Cdk9 activity also partially rescued chromosome segregation phenotypes of H2Bub1 mutants. In a genome-wide analysis, loss of H2Bub1 led to increased antisense transcripts at over 500 protein-coding genes in H2Bub1 mutants; for a subset of these, including several genes involved in chromosome segregation and chromatin assembly, antisense derepression was Cdk9-dependent. Our results highlight antisense suppression as a key feature of cell cycle-dependent gene regulation by H2Bub1, and suggest that aberrant transcription elongation may underlie the effects of H2Bub1 loss on cell cycle progression.

中文翻译：

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组蛋白 H2B 泛素化通过抑制裂殖酵母中的反义转录来调节组蛋白基因表达。


组蛋白 H2B 单泛素化 (H2Bub1) 与 RNA 聚合酶 II 转录延伸紧密相关，并且也直接参与 DNA 复制和修复。 H2Bub1 的缺失与细胞周期进展的缺陷相关，但这些缺陷与其各种功能以及所涉及的潜在机制之间的关系尚不清楚。在这里，我们描述了 H2Bub1 在裂殖酵母裂殖酵母复制依赖性组蛋白基因调节中的作用。 H2Bub1 通过抑制 ams2+ 的反义转录来间接激活组蛋白基因，ams2+ 是编码 GATA 型转录因子的基因，可激活组蛋白基因，并且是着丝粒染色质组装所必需的。 H2B 中缺乏泛素化位点或 H2B 特异性 E3 泛素连接酶 Brl2 的突变体的 ams2+ 反义转录物水平升高，Ams2 蛋白水平降低。这些缺陷在抑制 Cdk9（正转录延伸因子 b (P-TEFb) 激酶成分的直系同源物）后得到逆转，表明它们可能是由异常转录延伸引起的。 Cdk9 活性降低也部分挽救了 H2Bub1 突变体的染色体分离表型。在全基因组分析中，H2Bub1 的缺失导致 H2Bub1 突变体中 500 多个蛋白质编码基因的反义转录本增加；对于其中的一个子集，包括涉及染色体分离和染色质组装的几个基因，反义去阻抑是 Cdk9 依赖性的。我们的结果强调反义抑制是 H2Bub1 细胞周期依赖性基因调控的一个关键特征，并表明异常转录延伸可能是 H2Bub1 丢失对细胞周期进展影响的基础。