Persulfidation as a protective method against overoxidation of Peroxiredoxin 2

Student thesis: Master's Thesis


Peroxiredoxins (Prdxs) are essential proteins involved in maintaining the balance between the production and elimination of intracellular hydrogen peroxide (H2O2). The main function of Prdxs is to scavenge H2O2 (peroxidase function), but they also participate in cell signaling processes through the transfer of the oxidative equivalent to target proteins (redox -relay function). Furthermore, at high intracellular H2O2 concentrations, Prdxs get overoxidized, losing their activity as peroxidases but behaving as molecular chaperones. Within the mammalian isoforms, peroxiredoxin 2 (Prdx2) stands out for being the most reactive towards H2O2, with reaction rates of 107–108 M−1 s−1, but also the most sensitive to overoxidation with reaction rates of 1.2 x 104 M−1 s−1. When overoxidized, Prdx2 forms sulfinic and sulfonic acids (Cysp-SO2/3H), which are irreversible states. Today, it still remains a mystery how Prdx2 can be active in environments where high H2O2 concentrations are present. It is known that cells present protection mechanisms against overoxidation, like persulfidation. Persulfidation is a type of post-translational modification (PTM) of protein that involves persulfide formation through cysteine modification. When working in vitro, it is very difficult to control the redox stateofproteinsandavoidcysteineoveroxidation. Untilnow,severalphysicalstrategiesare performed, but a more specific protection of Cys residues would be preferred. For this reason, the objective of this project is to determine if persulfidation can protect Prdx2 from overoxidation in vitro. Here, Na2S4 and Na2S salts have been evaluated as a source of persulfide. Moreover, the effect of persulfidation on the stability, oligomerization, and protection of H2O2 has been assessed. The peroxidase activity of reconstituted Prdx2 has been also determined. Finally, crystallization screenings of persulfidated Prdx2 have been set in order to solve the X-ray structure of this PTM on Prdx2.
Date of Award30 Jun 2023
Original languageEnglish

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