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Updated: Aug 5, 2026
11:36
In Vitro Ubiquitination and Deubiquitination Assays of Nucleosomal Histones
Published on: July 25, 2019
Functional interplay between H2B ubiquitylation and H2A.Z deposition
Younus A Bhat1, Ivano Mocavini2, Erin O'Donnell3
1Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA, USA.
The Journal of Biological Chemistry
|July 28, 2026
Summary
The Bre1 enzyme
Area of Science:
- Molecular Biology
- Epigenetics
- Chromatin Biology
Background:
- Bre1 ubiquitinating enzyme monoubiquitylates histone H2B-K120/K123, impacting transcription.
- SWR1C chromatin remodeler deposits histone variant H2A.Z at similar nucleosomes.
- Loss of both Bre1 and Swr1 leads to inviability, suggesting a critical shared function.
Purpose of the Study:
- Investigate the functional interplay between H2B ubiquitylation and H2A.Z deposition.
- Determine how H2B-K123ub affects SWR1C activity.
- Elucidate the role of H2B-K123ub in H2A.Z genomic organization, particularly during replication stress.
Main Methods:
- Utilized recombinant nucleosomes to assess SWR1C activity in vitro.
- Analyzed genomic organization of H2A.Z in yeast strains lacking Bre1.
- Examined H2A.Z re-localization during replication stress.
Main Results:
- H2B-K123ub strongly inhibits the H2A.Z deposition activity of SWR1C.
- Loss of H2B-K123ub did not significantly alter H2A.Z genomic distribution under normal conditions.
- H2B-K123ub is essential for H2A.Z relocation from promoters to coding regions during replication stress.
Conclusions:
- H2B ubiquitylation and H2A.Z deposition are intricately linked.
- H2B-K123ub acts as an inhibitor of SWR1C-mediated H2A.Z deposition.
- H2B-K123ub regulates H2A.Z localization dynamics in response to replication stress.
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