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  • Phase separation promotes a highly active oligomeric scaffold of the MLL1 core complex for regulation of histone H3K4 methylation
Title: Phase separation promotes a highly active oligomeric scaffold of the MLL1 core complex for regulation of histone H3K4 methylation
Enzymes that regulate the degree of histone H3 lysine 4 (H3K4) methylation are crucial for proper cellular differentiation and are frequently mutated in cancer. The Mixed lineage leukemia (MLL) family of enzymes deposit H3K4 mono-, di-, or trimethylation at distinct genomic locations, requiring precise spatial and temporal control. Despite evidence that the degree of H3K4 methylation is controlled in part by a hierarchical assembly pathway with key subcomplex components, we previously found that the assembled state of the MLL1 core complex is not favored at physiological temperature. To better understand this paradox, we tested the hypothesis that increasing the concentration of subunits in a biomolecular condensate overcomes this thermodynamic barrier via mass action. Here, we demonstrate that MLL1 core complex phase separation stimulates enzymatic activity up to 60-fold but not primarily by concentrating subunits into droplets. Instead, we found that stimulated activity is largely due to the formation of an altered oligomeric scaffold that greatly reduces substrate Km. We posit that phase separation–induced scaffolding of the MLL1 core complex is a potential “switch-like” mechanism for spatiotemporal control of H3K4 methylation through the rapid formation or dissolution of biomolecular condensates within RNA Pol II transcription factories.  more » « less
Award ID(s):
1932730
PAR ID:
10529154
Author(s) / Creator(s):
; ;
Publisher / Repository:
Elsevier Inc on behalf of American Society for Biochemistry and Molecular B
Date Published:
Journal Name:
Journal of Biological Chemistry
Volume:
299
Issue:
10
ISSN:
0021-9258
Page Range / eLocation ID:
105204
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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