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Surface cysteines could protect the SARS-CoV-2 main protease from oxidative damage
Raheleh Ravanfar1, Yuling Sheng1, Mona Shahgholi1
1Beckman Institute, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA.
Journal of Inorganic Biochemistry
|June 8, 2022
Summary
Surface cysteines on SARS-CoV-2 main protease (Mpro) may protect the active site from oxidative damage. Mutating these cysteines did not significantly impact enzyme activity, suggesting a redox protective role.
Area of Science:
- Biochemistry
- Virology
- Structural Biology
Background:
- The SARS-CoV-2 main protease (Mpro) is essential for viral replication, cleaving viral polyproteins.
- Mpro possesses numerous noncatalytic cysteine residues, whose function remains unclear.
- These cysteines are not involved in disulfide bonds, suggesting a role beyond structural stabilization.
Purpose of the Study:
- To investigate the potential role of surface cysteine residues in protecting the Mpro active site from oxidation.
- To explore the involvement of Mpro cysteines in redox processes.
Main Methods:
- Enzyme kinetics assays were performed on wild-type and mutant Mpro.
- Site-directed mutagenesis was used to replace surface cysteine residues with serine.
Main Results:
- Mutating three surface cysteine residues to serine did not significantly alter Mpro enzyme activity.
- This suggests these surface cysteines are not critical for catalytic function.
Conclusions:
- Surface cysteines on Mpro may play a protective role against oxidation by reactive oxygen species (ROS).
- These cysteines could shield the active-site cysteine (Cys145) from oxidative damage, preserving enzyme function.
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