Abstract
The enzyme thioredoxin reductase (TrxR) contributes to cellular oxidant defense and metabolism with its redox partner thioredoxin (Trx). The thioredoxin system is highly conserved across biological domains, but TrxRs evolved convergently into the low molecular weight (LMW) form in microbial and fungal species and the high molecular weight form (HMW) in eukaryotes. Both forms have two active site cysteines that reduce thioredoxin via the formation of reversible disulfide bonds. In addition to the catalytic cysteine, an additional cysteine found near the C-terminus of the protein has shown what we initially thought was a pattern of conservation within Gram-negative bacteria and fungal species. Further explorations into this cysteine indicated that it forms intrasubunit disulfides in the presence of the disulfide donor DTNB, potentially acting as a non-active site redox center within the protein. Here, I test whether other strong oxidants (diamide and hypochlorite) can oxidize different microbial TrxRs, as well as further investigating the patterns of conservation in the bacterial domain. Additionally, we look into potential mechanisms of reduction at this site by either self-reduction or reduction by Trx. After looking further into the evolution of TrxR there was a much broader pattern of conservation across bacterial phyla than cannot easily be explained via a Gram positive/negative delineation. We also found evidence of similar intrasubunit disulfide formation, as seen in Trr1, in different microbial species as well as across the panel of oxidants. Our results thus far indicate that the C-terminal cysteine could potentially act as a regulatory cite. Future work will include mapping disulfide formation by mass spectrometry, looking for oxidation in vivo, and finding potential redox partners that act through the C-terminal cysteine.
Advisor
West, James
Department
Biochemistry and Molecular Biology
Recommended Citation
Showalter, Abigail, "Characterization of Oxidation-Prone Cysteines in Microbial Thioredoxin Reductases" (2024). Senior Independent Study Theses. Paper 11180.
https://openworks.wooster.edu/independentstudy/11180
Disciplines
Biochemistry | Molecular Biology
Keywords
Thioredoxin Reductase, Thioredoxin System
Publication Date
2024
Degree Granted
Bachelor of Arts
Document Type
Senior Independent Study Thesis
© Copyright 2024 Abigail Showalter