Histone H3 lysine 27 methylation catalyzed by polycomb repressive complex 2 (PRC2) is conserved from fungi to humans and represses gene transcription. However, the mechanism for recognition of methylated H3K27 remains unclear, especially in fungi. Here, we found that the bromo-adjacent homology (BAH)-plant homeodomain (PHD) domain containing protein BAH–PHD protein 1 (BP1) is a reader of H3K27 methylation in the cereal fungal pathogen Fusarium graminearum. BP1 interacts with the core PRC2 component Suz12 and directly binds methylated H3K27. BP1 is distributed in a subset of genomic regions marked by H3K27me3 and co-represses gene transcription. The BP1 deletion mutant shows identical phenotypes on mycelial growth and virulence, as well as similar expression profiles of secondary metabolite genes to the strain lacking the H3K27 methyltransferase Kmt6. More importantly, BP1 can directly bind DNA through its PHD finger, which might increase nucleosome residence and subsequently reinforce transcriptional repression in H3K27me3-marked target regions. A phylogenetic analysis showed that BP1 orthologs are mainly conserved in fungi. Overall, our findings provide novel insights into the mechanism by which PRC2 mediates gene repression in fungi, which is distinct from the PRC1-PRC2 system in plants and mammals.

中文翻译：

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Fusarium BP1 是 H3K27 甲基化的阅读器

由多梳抑制复合物 2 (PRC2) 催化的组蛋白 H3 赖氨酸 27 甲基化从真菌到人类是保守的，并抑制基因转录。然而，识别甲基化 H3K27 的机制仍不清楚，尤其是在真菌中。在这里，我们发现含有蛋白质 BAH-PHD 蛋白 1 (BP1) 的溴相邻同源 (BAH)-植物同源结构域 (PHD) 结构域是谷类真菌病原体禾谷镰刀菌中 H3K27 甲基化的读取器。BP1 与核心 PRC2 组件 Suz12 相互作用并直接结合甲基化 H3K27。BP1 分布在由 H3K27me3 标记的基因组区域的子集中，并共同抑制基因转录。BP1缺失突变体在菌丝体生长和毒力方面表现出相同的表型，以及与缺乏 H3K27 甲基转移酶 Kmt6 的菌株相似的次级代谢物基因的表达谱。更重要的是，BP1 可以通过其 PHD 指直接结合 DNA，这可能会增加核小体的驻留并随后加强 H3K27me3 标记的靶区域的转录抑制。系统发育分析表明，BP1 直系同源物主要在真菌中保守。总体而言，我们的研究结果为PRC2介导真菌基因抑制的机制提供了新的见解，这与植物和哺乳动物中的PRC1-PRC2系统不同。系统发育分析表明，BP1 直系同源物主要在真菌中保守。总体而言，我们的研究结果为PRC2介导真菌基因抑制的机制提供了新的见解，这与植物和哺乳动物中的PRC1-PRC2系统不同。系统发育分析表明，BP1 直系同源物主要在真菌中保守。总体而言，我们的研究结果为PRC2介导真菌基因抑制的机制提供了新的见解，这与植物和哺乳动物中的PRC1-PRC2系统不同。