Reversible oxidative signaling in Chlamydomonas following nitrogen deprivation

As global temperatures climb to historic highs, the far-reaching effects of climate change have impacted agricultural nutrient availability. This has extended to low latitude oceans, where a deficit in both nitrogen and phosphorus stores has led to dramatic decreases in carbon sequestration in oceanic phytoplankton. Although Chlamydomonas reinhardtii, a freshwater model green alga, has shown drastic systems-level alterations following nitrogen deprivation, the mechanism(s) through which these alterations are triggered and regulated are unclear. This study examined the role of reversible oxidative signaling in the nitrogen stress response of C. reinhardtii. Using oxidized cysteine resin-assisted capture enrichment coupled with label-free quantitative proteomics, 7,889 unique oxidized cysteine thiol identifiers were quantified, with 231 significantly changing peptides from 184 proteins following 2 h of nitrogen deprivation. These results demonstrate proteins affected by oxidation involved in nitrogen assimilation, amino acid metabolism, photosynthesis, and other metabolic processes. An enhanced role of non-damaging oxidative pathways is observed throughout the photosynthetic apparatus that provides a framework for further analysis in phototrophs.