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In Vitro Analysis of E3 Ubiquitin Ligase Function
Published on: May 14, 2021
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Ubiquitin is a carbon dioxide-binding protein
Victoria L Linthwaite1, Wes Pawloski2, Hamish B Pegg1
1Department of Biosciences, Durham University, Durham DH1 3LE, UK.
Science Advances
|September 24, 2021
Summary
Ubiquitin binds carbon dioxide (CO2) through carbamylation, a reversible modification. This finding reveals how cells sense and respond to changing CO2 levels, impacting key cellular pathways.
Area of Science:
- Biochemistry
- Molecular Biology
- Proteomics
Background:
- Carbon dioxide (CO2) regulation of molecular processes is critical.
- CO2 can reversibly modify proteins via carbamylation.
- Chemical proteomics tools are needed to identify CO2-binding proteins.
Purpose of the Study:
- To identify mammalian CO2-binding proteins.
- To investigate the role of carbamylation in CO2 sensing.
- To explore the impact of CO2 on ubiquitin function.
Main Methods:
- Utilized triethyloxonium (TEO) ion for covalent trapping of carbamates.
- Employed 13C-NMR spectroscopy to confirm carbamate formation on ubiquitin.
- Assessed the effects of physiological CO2 levels on ubiquitin conjugation and NF-κB pathway activation.
Main Results:
- Identified ubiquitin as a mammalian CO2-binding protein.
- Demonstrated CO2 carbamylation on ubiquitin's N-terminus and specific lysine residues (K6, K33, K48, K63).
- Showed that elevated CO2 reduces K48 ubiquitin conjugation and down-regulates the NF-κB pathway.
Conclusions:
- Ubiquitin functions as a CO2 sensor in mammalian cells.
- Carbamylation is a key mechanism for cellular response to CO2 fluctuations.
- CO2-mediated regulation of ubiquitin impacts cellular signaling pathways like NF-κB.
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