Theoretical Biology and Bioinformatics, Department of Biology, Science Faculty, Utrecht University, Utrecht, Netherlands.
Hubrecht institute, Royal Netherlands Academy of Arts and Sciences, Utrecht, Netherlands.
Commun Biol. 2023 Nov 10;6(1):1144. doi: 10.1038/s42003-023-05501-x.
Polycomb group proteins, as part of the Polycomb repressive complexes, are essential in gene repression through chromatin compaction by canonical PRC1, mono-ubiquitylation of histone H2A by non-canonical PRC1 and tri-methylation of histone H3K27 by PRC2. Despite prevalent models emphasizing tight functional coupling between PRC1 and PRC2, it remains unclear whether this paradigm indeed reflects the evolution and functioning of these complexes. Here, we conduct a comprehensive analysis of the presence or absence of cPRC1, nPRC1 and PRC2 across the entire eukaryotic tree of life, and find that both complexes were present in the Last Eukaryotic Common Ancestor (LECA). Strikingly, ~42% of organisms contain only PRC1 or PRC2, showing that their evolution since LECA is largely uncoupled. The identification of ncPRC1-defining subunits in unicellular relatives of animals and fungi suggests ncPRC1 originated before cPRC1, and we propose a scenario for the evolution of cPRC1 from ncPRC1. Together, our results suggest that crosstalk between these complexes is a secondary development in evolution.
多梳蛋白组蛋白作为多梳抑制复合物的一部分，通过经典的 PRC1 使染色质紧缩、非经典的 PRC1 使组蛋白 H2A 单泛素化以及 PRC2 使组蛋白 H3K27 三甲基化，从而在基因抑制中发挥重要作用。尽管普遍的模型强调 PRC1 和 PRC2 之间的紧密功能耦合，但尚不清楚这一范例是否确实反映了这些复合物的进化和功能。在这里，我们对整个真核生物进化树中 cPRC1、nPRC1 和 PRC2 的存在或缺失进行了全面分析，结果发现这两个复合物都存在于最后的真核生物共同祖先（LECA）中。引人注目的是，约 42%的生物只含有 PRC1 或 PRC2，表明自 LECA 以来它们的进化在很大程度上是不耦合的。在动物和真菌的单细胞亲属中鉴定出 ncPRC1 定义亚基表明 ncPRC1 起源于 cPRC1 之前，我们提出了 cPRC1 从 ncPRC1 进化而来的情景。总之，我们的研究结果表明，这些复合物之间的串扰是进化过程中的二次发育。
