Gail Emma H, Healy Evan, Flanigan Sarena F, Jones Natasha, Ng Xiao Han, Uckelmann Michael, Levina Vitalina, Zhang Qi, Davidovich Chen
Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria, Australia.
South Australian immunoGENomics Cancer Institute (SAiGENCI), Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, South Australia, Australia.
Nat Genet. 2024 Jun;56(6):1193-1202. doi: 10.1038/s41588-024-01740-8. Epub 2024 May 14.
Polycomb repressive complex 2 (PRC2) interacts with RNA in cells, but there is no consensus on how RNA regulates PRC2 canonical functions, including chromatin modification and the maintenance of transcription programs in lineage-committed cells. We assayed two separation-of-function mutants of the PRC2 catalytic subunit EZH2, defective in RNA binding but functional in methyltransferase activity. We find that part of the RNA-binding surface of EZH2 is required for chromatin modification, yet this activity is independent of RNA. Mechanistically, the RNA-binding surface within EZH2 is required for chromatin modification in vitro and in cells, through interactions with nucleosomal DNA. Contrarily, an RNA-binding-defective mutant exhibited normal chromatin modification activity in vitro and in lineage-committed cells, accompanied by normal gene repression activity. Collectively, we show that part of the RNA-binding surface of EZH2, rather than the RNA-binding activity per se, is required for the histone methylation in vitro and in cells, through interactions with the substrate nucleosome.
多梳抑制复合物2（PRC2）在细胞中与RNA相互作用，但关于RNA如何调节PRC2的经典功能，包括染色质修饰和谱系定向细胞中转录程序的维持，目前尚无共识。我们检测了PRC2催化亚基EZH2的两个功能分离突变体，它们在RNA结合方面存在缺陷，但甲基转移酶活性正常。我们发现，EZH2的部分RNA结合表面对于染色质修饰是必需的，但这种活性独立于RNA。从机制上讲，EZH2内的RNA结合表面通过与核小体DNA的相互作用，在体外和细胞中对于染色质修饰是必需的。相反，一个RNA结合缺陷突变体在体外和谱系定向细胞中表现出正常的染色质修饰活性，并伴有正常的基因抑制活性。总体而言，我们表明，通过与底物核小体的相互作用，EZH2的部分RNA结合表面而非RNA结合活性本身，在体外和细胞中对于组蛋白甲基化是必需的。
