Deciphering the Proteotoxic Stress Responses Triggered by the Perturbed Thylakoid Proteostasis in Arabidopsis

Abstract

Here, we explored heat dependent thylakoid FtsH protease substrates and investigated proteotoxicity induced by thermal damage and processive protease dysfunction on the thylakoid membrane. Through our thylakoid enriched proteome analysis and biochemical experiments, carbonylated stromal proteins were suggested as possible FtsH targets. Furthermore, we observed in the thylakoid fractions in the absence of FtsH stromal reactive oxygen species-detoxifying enzymes, as well as heat shock proteins and chaperones, which are known to be upregulated at the transcriptional level when this protease is absent, which is called the damaged protein response, resembling unfolded protein response in eukaryotic cells. Interestingly, the thylakoid-enriched high-density fractions included stromal translation factors and RNA-binding proteins, along with aminoacyl-tRNA synthetase, reminiscent of the formation of stress granules. Unexpectedly, extraplastid proteins such as mitochondrial chaperones, peroxidase, tricarboxylic acid cycle and respiratory chain enzymes, as well as cytosolic ribosomes, translation factors, heat shock proteins, antioxidants and metabolic enzymes, were also found deposited in the high-density fractions depending on the loss of thylakoid FtsH, with more prominent effects of thermal stress on the cytosolic proteins. This may reflect intracellular adaptation to the proteotoxic influences from the organelle.

Florpyrauxifen-Benzyl Selectivity to Rice

“…OsGSTL2 transgenic rice improves glyphosate and chlorsulfuron tolerance [55]. OsGSTL3 confers quizalofop-p-ethyl resistance to Polypogon fugax [58] Herein, it was observed that there was a differential profile in the expression of OsGSTL3 as a product of temperature changes over time, probably by its role as ROS scavenger [59]. However, it cannot be proven if the FPB spraying caused an overexpression.…”

A proteostasis network safeguards the chloroplast proteome

“…In agreement with this hypothesis, proteome analysis of chloroplast thylakoid fractions depleted of the FTSH protease under heat stress identified several extraplastidial cytosolic proteins. However, it is unclear how cytosolic proteins found in thylakoid fractions of heat-treated plants lacking FTSH could be relocated into the chloroplast [ 72 ]. Future efforts must be made to unveil if chloroplasts are capable of importing misfolded cytosolic proteins for further degradation.…”