Enzymes degraded under high light maintain proteostasis by transcriptional regulation in Arabidopsis

ABSTRACT: Photo-inhibitory high-light stress induces damage to photosystems and changes a myriad of metabolic processes in plants. In Arabidopsis it leads to increased abundance of markers of protein degradation and transcriptional upregulation of proteases and proteolytic machinery, but proteostasis is largely maintained. To identify specific enzymes degrading at a faster rate under high light conditions, we developed a 13C partial labelling approach to measure rates of turnover of specific proteins in Arabidopsis rosettes. We identified 73 proteins with rates of protein degradation enhanced by high-light. In addition to the expected increase in degradation rate of the photosystem II (PSII) D1 subunit, we discovered significant increases in degradation rate for specific molecular chaperones, nitrate reductase, glyceraldehyde-3 phosphate dehydrogenase, and phosphoglycerate kinase. Significant increases in degradation of 65 other plastid, mitochondrial, peroxisomal, and cytosolic enzymes were also found, including factors involved in redox shuttles within and between organelles and the cytosol. Coupled analysis of protein degradation rate, transcriptional rate, and protein abundance revealed that 57% of the nuclear-encoded enzymes with higher degradation rates also had high light-induced transcriptional responses, ensuring proteostasis. In contrast, plastid-encoded proteins with enhanced turnover rates showed decreased transcript abundances and must maintain protein abundance by other processes. This analysis reveals a light-induced transcriptional program for nuclear-encoded genes, beyond the regulation of PSII D1 subunit and the function of PSII, to replace key protein degradation targets in plants and ensure proteostasis under high-light stress.

ORGANISM(S): Arabidopsis thaliana

PROVIDER: GSE131545 | GEO | 2022/01/19

REPOSITORIES: GEO