Single Molecule Mass Photometry Reveals Dynamic Oligomerization of Plant and Human Peroxiredoxins for Functional Conservation and Diversification

Single molecule mass photometry was used to study the dynamic equilibria of the ubiquitous and highly abundant 2-Cysteine peroxiredoxins (2-CysPRX). 2-CysPRXs adopt distinct functions in all cells dependent on their oligomeric conformation ranging from dimers to decamers and high molecular weight aggregates (HMW). The oligomeric state depends on the redox state of their catalytic cysteinyl residues. To which degree they interconvert, how the interconversion is regulated, and how the oligomerisation propensity is organism specific remains, however, poorly understood. The dynamics differs between wild-type and single point mutants affecting the oligomerization interfaces, with concomitant changes to function. Titrating concentration and redox state of Arabidopsis thaliana and human 2-CysPRXs revealed features conserved among all 2-CysPRX and clear differences concerning oligomer transitions, the occurrence of transition states and the formation of HMW which are associated with chaperone activity or storage. The results indicate functional differentiation of human 2-CysPRXs. Our results point to a diversified functionality of oligomerization for 2-CysPRXs and illustrate the power of mass photometry to non-invasively quantify oligomer distributions in a redox environment. This knowledge is important to fully address and model PRX function in cell redox signaling e.g., in photosynthesis, cardiovascular and neurological diseases or carcinogenesis.