Shashank Raj Pandey | 2025 I.S. Symposium

Name: Shashank Raj Pandey
Title: Possible Redox Roles of Non-Active Site Cysteines in Yeast Mitochondrial Thioredoxin 3
Major: Biochemistry and Molecular Biology
Advisors: James West; Mark Snider

Thioredoxins (Trxs) are highly conserved oxidoreductase enzymes that maintain cellular redox balance by reducing disulfide bonds in oxidized proteins, thus protecting cells from oxidative damage. While the active-site cysteines of mitochondrial thioredoxin (Trx3) in Saccharomyces cerevisiae are well-characterized, the role of non-active site cysteines remains largely unexplored. This study primarily investigates the functional importance of these residues under oxidative stress and, secondarily, Trx3 branched-chain amino acid (BCAA) limitation conditions. Phenotypic analysis demonstrated that yeast strains expressing the Trx3 protein relatively resisted oxidative stress, whereas strains expressing cysteine mutants (C80S, C92S, and C80,92S) exhibited reduced growth under similar stress conditions. Western blotting and purification experiments revealed that mutations in non-active site cysteines result in lower protein expression and stability, suggesting that these cysteines may contribute to maintaining structural integrity rather than directly catalyzing redox reactions. These findings indicate that non-active site cysteines in Trx3 potentially play crucial roles in maintaining protein stability and potentially regulating protein-protein interactions under oxidative stress. Future research should focus on detailed structural and biochemical analyses to further elucidate the specific mechanisms by which these residues influence Trx3 function and stability.

Posted in Symposium 2025 on May 1, 2025.