Not changes in membrane fluidity but proteotoxic stress triggers heat shock protein expression in <scp><i>Chlamydomonas reinhardtii</i></scp>

Rütgers, Mark; Muranaka, Ligia Segatto; Schulz-Raffelt, Miriam; Thoms, Sylvia; Schurig, J.; Willmund, Felix; Schroda, Michael

doi:10.1111/pce.13060

Cited by 29 publications

(44 citation statements)

References 86 publications

(172 reference statements)

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“…7B) were significantly upregulated in mutant cells, as observed, for example, during severe proteotoxic stress (Schroda et al, 2015). However, we repeatedly noticed a very mild upregulation of the small Hsp HSP22E/F, which has previously been shown to be a highly sensitive marker for protein unfolding in chloroplasts (Rütgers et al, 2017b). We further tested mutant lines for increased protein misfolding and aggregation with a focus on chloroplast-encoded proteins.…”

Section: Deletion Of Chloroplast Tig1 Results In a Perturbed Energy Bmentioning

confidence: 74%

The Role of Plastidic Trigger Factor Serving Protein Biogenesis in Green Algae and Land Plants

et al. 2019

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Biochemical processes in chloroplasts are important for virtually all life forms. Tight regulation of protein homeostasis and the coordinated assembly of protein complexes, composed of both imported and locally synthesized subunits, are vital to plastid functionality. Protein biogenesis requires the action of cotranslationally acting molecular chaperones. One such chaperone is trigger factor (TF), which is known to cotranslationally bind most newly synthesized proteins in bacteria, thereby assisting their correct folding and maturation. However, how these processes are regulated in chloroplasts remains poorly understood. We report here functional investigation of chloroplast-localized TF (TIG1) in the green alga (Chlamydomonas reinhardtii) and the vascular land plant Arabidopsis (Arabidopsis thaliana). We show that chloroplastic TIG1 evolved as a specialized chaperone. Unlike other plastidic chaperones that are functionally interchangeable with their prokaryotic counterpart, TIG1 was not able to complement the broadly acting ortholog in Escherichia coli. Whereas general chaperone properties such as the prevention of aggregates or substrate recognition seems to be conserved between bacterial and plastidic TFs, plant TIG1s differed by associating with only a relatively small population of translating ribosomes. Furthermore, a reduction of plastidic TIG1 levels leads to deregulated protein biogenesis at the expense of increased translation, thereby disrupting the chloroplast energy household. This suggests a central role of TIG1 in protein biogenesis in the chloroplast.

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Section: Deletion Of Chloroplast Tig1 Results In a Perturbed Energy Bmentioning

confidence: 74%

The Role of Plastidic Trigger Factor Serving Protein Biogenesis in Green Algae and Land Plants

et al. 2019

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“…The proteolytic activity of DEG1C increased at temperatures of 37°C and above, presumably because higher temperatures promote substrate unfolding (Kolmar et al, 1996;Kim et al, 1999;Chassin et al, 2002;Ge et al, 2014). Accordingly, at these temperatures the chloroplast small heat shock proteins HSP22E and HSP22F were found to accumulate and to integrate into forming protein aggregates (Rütgers et al, 2017b). Under standard growth Figure 8.…”

Section: Discussionmentioning

confidence: 99%

The Chlamydomonas deg1c Mutant Accumulates Proteins Involved in High Light Acclimation

et al. 2019

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Degradation of periplasmic proteins (Deg)/high temperature requirement A (HtrA) proteases are ATP-independent Ser endopeptidases that perform key aspects of protein quality control in all domains of life. Here, we characterized Chlamydomonas reinhardtii DEG1C, which together with DEG1A and DEG1B is orthologous to Arabidopsis (Arabidopsis thaliana) Deg1 in the thylakoid lumen. We show that DEG1C is localized to the stroma and the periphery of thylakoid membranes. Purified DEG1C exhibited high proteolytic activity against unfolded model substrates and its activity increased with temperature and pH. DEG1C forms monomers, trimers, and hexamers that are in dynamic equilibrium. DEG1C protein levels increased upon nitrogen, sulfur, and phosphorus starvation; under heat, oxidative, and high light stress; and when Secmediated protein translocation was impaired. DEG1C depletion was not associated with any obvious aberrant phenotypes under nonstress conditions, high light exposure, or heat stress. However, quantitative shotgun proteomics revealed differences in the abundance of 307 proteins between a deg1c knockout mutant and the wild type under nonstress conditions. Among the 115 upregulated proteins are PSII biogenesis factors, FtsH proteases, and proteins normally involved in high light responses, including the carbon dioxide concentrating mechanism, photorespiration, antioxidant defense, and photoprotection. We propose that the lack of DEG1C activity leads to a physiological state of the cells resembling that induced by high light intensities and therefore triggers high light protection responses.

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“…Salt stress can increase the rate of protein unfolding; challenge cellular protein homeostasis for the available folding capacity becomes insufficient. Molecular chaperones or heat shock proteins are a large family of proteins that have the important function of helping other proteins fold and repair misfolding [35,36]. HSP70B and HSP90A play important roles in plant growth and responses to environmental stimuli [37].…”

Section: Discussionmentioning

confidence: 99%

Identification of Early Salinity Stress-Responsive Proteins in Dunaliella salina by isobaric tags for relative and absolute quantitation (iTRAQ)-Based Quantitative Proteomic Analysis

Wang

Cong

Wang

et al. 2019

IJMS

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Salt stress is one of the most serious abiotic factors that inhibit plant growth. Dunaliella salina has been recognized as a model organism for stress response research due to its high capacity to tolerate extreme salt stress. A proteomic approach based on isobaric tags for relative and absolute quantitation (iTRAQ) was used to analyze the proteome of D. salina during early response to salt stress and identify the differentially abundant proteins (DAPs). A total of 141 DAPs were identified in salt-treated samples, including 75 upregulated and 66 downregulated DAPs after 3 and 24 h of salt stress. DAPs were annotated and classified into gene ontology functional groups. The Kyoto Encyclopedia of Genes and Genomes pathway analysis linked DAPs to tricarboxylic acid cycle, photosynthesis and oxidative phosphorylation. Using search tool for the retrieval of interacting genes (STRING) software, regulatory protein–protein interaction (PPI) networks of the DAPs containing 33 and 52 nodes were built at each time point, which showed that photosynthesis and ATP synthesis were crucial for the modulation of early salinity-responsive pathways. The corresponding transcript levels of five DAPs were quantified by quantitative real-time polymerase chain reaction (qRT-PCR). These results presented an overview of the systematic molecular response to salt stress. This study revealed a complex regulatory mechanism of early salt tolerance in D. salina and potentially contributes to developing strategies to improve stress resilience.

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Not changes in membrane fluidity but proteotoxic stress triggers heat shock protein expression in Chlamydomonas reinhardtii

Cited by 29 publications

References 86 publications

The Role of Plastidic Trigger Factor Serving Protein Biogenesis in Green Algae and Land Plants

The Role of Plastidic Trigger Factor Serving Protein Biogenesis in Green Algae and Land Plants

The Chlamydomonas deg1c Mutant Accumulates Proteins Involved in High Light Acclimation

Identification of Early Salinity Stress-Responsive Proteins in Dunaliella salina by isobaric tags for relative and absolute quantitation (iTRAQ)-Based Quantitative Proteomic Analysis

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