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Updated: Apr 24, 2026
Automated Sample Preparation for the Multiplexed Analysis of Single-Cell Histone Post-Translational Modifications (sc-hPTM2)
Published on: December 19, 2025
Strategy for "detoxification" of a cancer-derived histone mutant based on mapping its interaction with the
Zachary Z Brown1, Manuel M Müller, Siddhant U Jain
1Department of Chemistry, Princeton University , Princeton, New Jersey 08544, United States.
Abstract:
The histone methyltransferase PRC2 plays a central role in genomic stability and cellular development. Consequently, its misregulation has been implicated in several cancers. Recent work has shown that a histone H3 mutant, where the PRC2 substrate residue Lys27 is replaced by methionine, is also associated with cancer phenotypes and functions as an inhibitor of PRC2. Here we investigate the mechanism of this PRC2 inhibition through kinetic studies and photo-cross-linking. Efficient inhibition is dependent on (1) hydrophobic lysine isosteres blocking the active site, (2) proximal residues, and (3) the H3 tail forming extensive contacts with the EZH2 subunit of PRC2. We further show that naturally occurring post-translational modifications of the same H3 tail, both proximal and distal to K27M, can greatly diminish the inhibition of PRC2. These results suggest that this potent gain of function mutation may be "detoxified" by modulating alternate chromatin modification pathways.
Insights
A histone H3 mutation (K27M) inhibits the PRC2 complex, crucial for genomic stability and development. This inhibition can be reduced by natural modifications on the H3 tail, suggesting therapeutic potential.
Area of Science:
- Biochemistry
- Epigenetics
- Cancer Biology
Background:
- Polycomb repressive complex 2 (PRC2) is vital for genomic stability and cellular development.
- Misregulation of PRC2 is linked to various cancers.
- A specific histone H3 mutation (H3 K27M) inhibits PRC2 and is associated with cancer phenotypes.
Purpose of the Study:
- To elucidate the molecular mechanism by which the H3 K27M mutation inhibits PRC2.
- To investigate the structural and kinetic factors contributing to PRC2 inhibition by H3 K27M.
- To explore how natural post-translational modifications affect PRC2 inhibition by H3 K27M.
Main Methods:
- Kinetic studies to quantify enzyme activity and inhibition.
- Photo-cross-linking experiments to map protein-protein interactions.
- Biochemical analysis of histone modifications and their impact on PRC2 function.
Main Results:
- PRC2 inhibition by H3 K27M requires hydrophobic interactions in the active site and contacts with the EZH2 subunit.
- The H3 tail plays a critical role in mediating this inhibition.
- Naturally occurring post-translational modifications on the H3 tail significantly reduce PRC2 inhibition by H3 K27M.
Conclusions:
- The H3 K27M mutation potently inhibits PRC2 through specific structural interactions.
- Post-translational modifications on the H3 tail can counteract this inhibition.
- Targeting chromatin modification pathways may offer strategies to "detoxify" the oncogenic H3 K27M mutation.
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