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Updated: Mar 10, 2026
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In Vitro Ubiquitination and Deubiquitination Assays of Nucleosomal Histones
Published on: July 25, 2019
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Recognition of ubiquitinated nucleosomes
Michael T Morgan1, Cynthia Wolberger1
1Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Current Opinion in Structural Biology
|December 7, 2016
Summary
Histone ubiquitination regulates gene transcription and DNA repair. New structural studies reveal how enzymes recognize ubiquitinated histones, advancing our understanding of these crucial chromatin modifications.
Area of Science:
- Epigenetics and Molecular Biology
- Chromatin Biology
- Structural Biology
Background:
- Histone ubiquitination is a key epigenetic mark regulating gene transcription and DNA damage response.
- Understanding the structural mechanisms of histone ubiquitination recognition has been challenging due to technical difficulties.
- Specialized protein subunits are involved in targeting deubiquitinating enzymes (DUBs) to their histone substrates.
Purpose of the Study:
- To elucidate the structural basis of histone ubiquitination recognition by chromatin-modifying complexes.
- To provide mechanistic insights into how DUBs target ubiquitinated histones.
- To understand how distinct combinations of histone marks are recognized.
Main Methods:
- Single particle electron microscopy (cryo-EM) of SAGA coactivator complex bound to ubiquitinated nucleosomes.
- Cryo-EM analysis of 53BP1 bound to nucleosomes with specific histone modifications (ubiquitinated H2A, methylated H4).
Main Results:
- The structure of the SAGA DUB module bound to monoubiquitinated H2B reveals substrate targeting mechanisms.
- Cryo-EM of the intact SAGA complex shows engagement of DUB and HAT modules with nucleosomal substrates.
- Structural insights into how 53BP1 recognizes combined H2A ubiquitination and H4K20 methylation via multivalent interactions.
Conclusions:
- Structural studies provide unprecedented views of how chromatin-modifying enzymes recognize ubiquitinated histones.
- These findings advance the mechanistic understanding of non-degradative histone ubiquitination in gene regulation and DNA repair.
- Multivalent interactions are crucial for recognizing specific combinations of histone modifications, impacting cellular signaling pathways.
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