The methylation of histone 3 lysine 4 (H3K4) is carried out by an evolutionarily conserved family of methyltransferases referred to as complex of proteins associated with Set1 (COMPASS). The activity of the catalytic SET domain (su(var)3-9, enhancer-of-zeste, and trithorax) is endowed through forming a complex with a set of core proteins that are widely shared from yeast to humans. We obtained cryo-electron microscopy (cryo-EM) maps of the yeast Set1/COMPASS core complex at overall 4.0- to 4.4-Å resolution, providing insights into its structural organization and conformational dynamics. The Cps50 C-terminal tail weaves within the complex to provide a central scaffold for assembly. The SET domain, snugly positioned at the junction of the Y-shaped complex, is extensively contacted by Cps60 (Bre2), Cps50 (Swd1), and Cps30 (Swd3). The mobile SET-I motif of the SET domain is engaged by Cps30, explaining its key role in COMPASS catalytic activity toward higher H3K4 methylation states. The cryo-EM structure of a fully functional COMPASS complex reveals the intricate structural coordination of the methyltransferase subunit by its partner proteins.
Qu, Q., Takahashi, Y. hei, Yang, Y., Hu, H., Zhang, Y., Brunzelle, J. S., … Skiniotis, G. (2018). Structure and Conformational Dynamics of a COMPASS Histone H3K4 Methyltransferase Complex. Cell, 174(5), 1117-1126.e12. https://doi.org/10.1016/j.cell.2018.07.020