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Updated: Jul 3, 2025
08:33
Ubiquitin Chain Analysis by Parallel Reaction Monitoring
Published on: June 17, 2020
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Monoubiquitination empowers ubiquitin chain elongation
Kenneth Wu1, Robert J DeVita2, Zhen-Qiang Pan1
1Department of Oncological Sciences, The Icahn School of Medicine at Mount Sinai, New York, New York, USA.
The Journal of Biological Chemistry
|February 14, 2024
Summary
This study reveals how ubiquitination priming and extension work together. Monoubiquitinated beta-catenin efficiently undergoes further ubiquitination, showing dynamic interactions with E3 ligases.
Area of Science:
- Biochemistry
- Molecular Biology
- Cellular Biology
Background:
- Ubiquitination generates lysine 48-linked polyubiquitin chains for protein degradation.
- A priming/extending mechanism involves initial monoubiquitination followed by chain elongation.
Purpose of the Study:
- To investigate the priming/extending ubiquitination mechanism.
- To analyze the turnover and E3 ligase interactions of ubiquitinated substrates.
Main Methods:
- Reconstituted ubiquitination systems using CK1α and β-catenin substrates.
- Cullin-RING E3 Ub ligases (CRLs) CRL4CRBN and CRL1βTrCP.
- Priming E2 UbcH5c and elongating E2 Cdc34b.
- A novel "apyrase chase" strategy to uncouple priming and elongation.
Main Results:
- Highly robust turnover of monoubiquitinated β-catenin facilitates efficient polyubiquitination.
- Interactions between ubiquitinated β-catenin and CRL1βTrCP are dynamic.
- Ubiquitinated β-catenin exhibits enhanced resistance to inhibition, suggesting tighter E3 ligase binding.
Conclusions:
- Monoubiquitination is crucial for efficient polyubiquitin chain extension.
- Conjugated ubiquitin enhances substrate interactions with E3 ligases.
- The priming/extending mechanism is a robust pathway in ubiquitination.
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