Photosynthetic Metabolism and Nitrogen Reshuffling Are Regulated by Reversible Cysteine Thiol Oxidation Following Nitrogen Deprivation in Chlamydomonas

Abstract

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 mechanisms through which these alterations are triggered and regulated are not fully understood. 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, 7889 unique oxidized cysteine thiol identifiers were quantified, with 231 significantly changing peptides from 184 proteins following 2 h of nitrogen deprivation. These results demonstrate that the cellular response to nitrogen assimilation, photosynthesis, pigment biosynthesis, and lipid metabolism are regulated by reversible oxidation. An enhanced role of non-damaging oxidative pathways is observed throughout the photosynthetic apparatus that provides a framework for further analysis in phototrophs.

MicroRNA Expression Profile Analysis of Chlamydomonas reinhardtii during Lipid Accumulation Process under Nitrogen Deprivation Stresses

“…The functional annotation chart of target genes for the nitrogen deficiency-responsive miRNAs revealed some factors involved in the regulation of lipids biosynthesis (acyl-CoA synthetase, fatty acid desaturase), lipid transport (long-chain acyl-CoA transporter), and fatty acid beta-oxidation (Pristanoyl-CoA/acyl-CoA oxidase), were all predicted, indicating that various aspects in the lipid metabolic process may be regulated by some nitrogen deficiency-responsive miRNAs in C. reinhardtii . A recent study found that under nitrogen stress, C. reinhardtii lipids synthesize related proteins: acetyl CoA synthetase, two fatty acid desaturases, and a phospholipase-B-like protein change rapidly, indicating a trend of transformation from metabolism to TAG synthesis at the post-transcriptional level [ 52 ], which is consistent with this study. Similarly, LIP4, a putative TAG lipase in C. reinhardtii, is transcriptionally upregulated in the presence of nitrogen deficiency and TAG accumulation [ 53 ].…”

Molecular Response of Ulva prolifera to Short-Term High Light Stress Revealed by a Multi-Omics Approach

“…Chlorophyll synthesis and catabolism were dynamically balanced, and the change in the ratio of Chls a/b under different physiological conditions was reflected in this experiment’s transcriptome data. After 12 h of high light treatment, the expressions of glutamate-1-semialdehyde 2,1-aminomutase-related genes ( Table 1 ) were up-regulated to promote the production of Chl b [ 47 , 48 ]. The expression level of pheophorbide hydrolase-related genes, which was the key rate-limiting enzyme of the chlorophyll catabolism pathway, was down-regulated.…”

Abscisic acid‐controlled redox proteome of Arabidopsis and its regulation by heterotrimeric Gβ protein

“…Protein‐level enrichment of reversible cysteine oxidation was performed as described previously (McConnell et al ., 2018; Smythers et al ., 2020). To show that alkylation of reduced cysteines was complete and to reduce false positive changes in reversible oxidation, a negative enrichment control was generated by pooling 15 μg from every sample (480 μg total) and then mock‐reduced with water.…”