Discovering genome-wide thiol-dependent metabolic regulation in photosynthesis with redox chemoproteomics

ended

Most organisms exhibit a diurnal metabolic cycle, especially phototrophs, whose metabolism is strictly dependent on light. Dark-light transitions are accompanied by dramatic changes in the redox state of photosynthetic components, which drives redox-based post-translational modification of protein cysteines, whose oxidation state can considerably impact protein activity, and thus regulate metabolism. Given the central role of redox metabolism in biology, the operation of thiol-disulphide based switches are well-appreciated as a metabolic acclimation strategy, and the study of cysteine modifications in proteomes is a major interest of contemporary biology. The objective of CHLARABIDOX is to go beyond inventories of redox modified proteins by monitoring the proteome-wide dynamics of disulphide-dithiol status in the context of a diurnal metabolic cycle in phototrophic eukaryotes, specifically, the green alga Chlamydomonas reinhardtii and the land plant Arabidopsis thaliana. An innovative chemoproteomic isoTOP-ABPP approach will be used in an experimental design with deep temporal resolution to capture a good fraction of the proteome with site specificity and quantitative information about reactivity. The discoveries will be made in the context of a body of literature on thioredoxin-dependent redox regulation of central carbon metabolism, which will serve as a priori validation. The outcome of the project is a proteome-wide view of the operation of regulatory redox sensors, anchored to accompanying rich datasets on physiology, metabolic potential, transcriptomics, proteomics and central metabolites, which would inform the operation of light-driven metabolic networks. Both systems are compatible with downstream modelling of diurnal metabolic fluxes and validation by reverse genetics approaches. A long term impact on strategies for manipulating metabolism for biofuels production, or manipulating photosynthesis for better acclimation to climate change is also envisioned.