Polycomb repressive complex 2 (PRC2) catalyzes methylation of histone H3 at lysine 27 (H3K27) in genomic regions of most eukaryotes and is critical for maintenance of the associated transcriptional repression. However, the mechanisms that shape the distribution of H3K27 methylation, such as recruitment of PRC2 to chromatin and/or stimulation of PRC2 activity, are unclear. Here, using a forward genetic approach in the model organism Neurospora crassa, we identified two alleles of a gene, NCU04278, encoding an unknown PRC2 accessory subunit (PAS). Loss of PAS resulted in losses of H3K27 methylation concentrated near the chromosome ends and derepression of a subset of associated subtelomeric genes. Immunoprecipitation followed by mass spectrometry confirmed reciprocal interactions between PAS and known PRC2 subunits, and sequence similarity searches demonstrated that PAS is not unique to N. crassa PAS homologs likely influence the distribution of H3K27 methylation and underlying gene repression in a variety of fungal lineages.

中文翻译：

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鉴定神经孢菌中亚端粒H3K27甲基化所需的PRC2辅助亚基。

在大多数真核生物的基因组区域中，多梳阻抑复合物2（PRC2）催化赖氨酸27（H3K27）处组蛋白H3的甲基化，对于维持相关的转录抑制至关重要。然而，尚不清楚影响H3K27甲基化分布的机制，例如将PRC2募集到染色质和/或刺激PRC2活性。在这里，在模型生物Neurospora crassa中使用正向遗传方法，我们鉴定了一个基因的两个等位基因，NCU04278，编码一个未知的PRC2辅助亚基（PAS）。PAS的丧失导致集中在染色体末端附近的H3K27甲基化的丧失和相关亚端粒基因的子集的抑制。免疫沉淀后再进行质谱分析，证实了PAS与已知的PRC2亚基之间的相互作用，