(B) Overall structure of PHF19-Tudor in complex with H3tK27me3. Bountra C, Edwards AM, Arrowsmith CH, Min JR, Structural Genomics Consortium (SGC) 2020. Crystal structure of PHF1 in complex with H3K36me3 substitution. RCSB Protein Data Lender. 6WAV Abstract The Polycomb repressive complex 2 (PRC2) is usually a multicomponent histone H3K27 methyltransferase complex, best known for silencing the genes during embryonic development. The Polycomb-like proteins PHF1, MTF2, and PHF19 are crucial components of Ro 28-1675 PRC2 by stimulating its catalytic activity in embryonic stem cells. The Tudor domains of PHF1/19 have been previously shown to be readers of OPD1 H3K36me3 in vitro. However, some other studies suggest that PHF1 and PHF19 co-localize with the H3K27me3 mark but not H3K36me3 in cells. Here, we provide further evidence that PHF1 co-localizes with H3t in testis and its Tudor domain name preferentially binds to H3tK27me3 over canonical H3K27me3 in vitro. Our complex structures of the Tudor domains of PHF1 and PHF19 with H3tK27me3 shed light on the molecular basis for preferential acknowledgement of H3tK27me3 by PHF1 and PHF19 over canonical H3K27me3, implicating that H3tK27me3 might be a physiological ligand of PHF1/19. gene was initially recognized in Drosophila (Duncan, 1982). In humans, you will find three PCL homologs, namely, PCL1, PCL2, and PCL3 (also known as PHF1, MTF2, and PHF19, respectively). In vivo and in vitro studies reveal that PHF1 stimulates the catalytic activity of PRC2 and plays an important role in the?silencing of the genes (Cao et al., 2008; Nekrasov et al., 2007; Sarma et al., 2008). PHF1 is also involved in response to DNA double-strand breaks (DSBs) through its conversation with Ku70/Ku80 in human cells (Hong et al., 2008) and regulates cellular quiescence and apoptosis by interacting with P53 (Brien et al., 2015; Yang et al., 2013). MTF2 is usually expressed abundantly in embryonic stem (ES) cells, wherein it regulates ES cell self-renewal, pluripotency, and cell fate decision (Walker et al., 2010; Walker et al., 2011). MTF2 also modulates somatic cell reprogramming as a key component of the PRC2 complex (Zhang et al., 2011). PHF19 modulates the PRC2 function by promoting H3K27 trimethylation, contributing to ES cell self-renewal (Hunkapiller et al., 2012). Overexpression of PHF1 and PHF19 is usually associated with many types of cancers (Liu et al., 2018; Wang et al., 2004). The three human PCL proteins all contain a single Tudor domain name followed by two herb homeodomain (PHD) fingers and an extended homologous (EH) domain name (Physique 1A). The Ro 28-1675 Tudor domains of PHF1 and PHF19 have been shown to be Ro 28-1675 readers of H3K36me3 in vitro and link PRC2 to the?chromatin (Ballar et al., 2012; Brien et al., 2012; Cai et al., 2013; Musselman et al., 2012; Qin et al., 2013). The PHD1 domain name of PHF1 can identify symmetric dimethylation of H4R3 (H4R3me2s;?Liu et al., 2018). The EH domain name, which binds to DNA, mediates the recruitment of PRC2 to CpG islands (Li et al., 2017). Recently, the C-terminal domain name of PHF19 stabilizes the dimerization of intrinsic PRC2 by interacting with SUZ12 and enhances the PRC2 binding to CpG islands (Chen et al., 2020; Chen et al., 2018). Previous data have suggested that PHF1 stimulates the H3K27me3 catalytic activity of PRC2 (Cao et al., 2008; Sarma et al., 2008) and H3K36me3 acknowledgement by PHF1 promotes the?spreading of PRC2 and H3K27me3 into H3K36me3-marked loci (Cai Ro 28-1675 et al., 2013). Similarly, the PHF19-H3K36me3 conversation is required for the full enzymatic activity of PRC2 and responsible for the recruitment of PRC2 and H3K36me3 demethylases NO66 and/or KDM2b to the target loci to remove the H3K36me3 active mark and facilitate deposition of H3K27me3 (Abed and Jones, 2012; Ballar et al., 2012;.