The Secret Life of Chloroplast Precursor Proteins in the Cytosol

Hristou, Athina; Grimmer, Julia; Baginsky, Sacha

doi:10.1016/j.molp.2020.07.004

Cited by 7 publications

(12 citation statements)

References 12 publications

(27 reference statements)

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“…It has been shown that phosphorylation of chloroplast-designated preproteins by cytosolic kinases is one of the key steps ensuring their sorting and specific targeting to this organelle during plastid maturation and stress response in Arabidopsis and pea ( Waegmann and Soll, 1996 ; Martin et al, 2006 ; Lamberti et al, 2011b ; Zufferey et al, 2017 ; Eisa et al, 2019 ; Hristou et al, 2020 ). The serine/threonine/tyrosine kinase 8 (STY8), STY17, and STY46 kinases phosphorylate chloroplast preprotein transit peptides ensuring their binding of a 14–3–3 dimer, which enhances association to the TOC receptor located at the outer envelope membrane of the chloroplast ( Martin et al, 2006 ; Lamberti et al, 2011a, 2011b).…”

Section: Discussionmentioning

confidence: 99%

The SnRK2.10 kinase mitigates the adverse effects of salinity by protecting photosynthetic machinery

et al. 2021

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SNF1-Related protein Kinases type 2 (SnRK2) are plant-specific enzymes widely distributed across the plant kingdom. They are key players controlling abscisic acid (ABA)-dependent and -independent signaling pathways in the plant response to osmotic stress. Here we established that SnRK2.4 and SnRK2.10, ABA-non activated kinases, are activated in Arabidopsis thaliana rosettes during the early response to salt stress and contribute to leaf growth retardation under prolonged salinity but act by maintaining different salt-triggered mechanisms. Under salinity, snrk2.10 insertion mutants were impaired in the reconstruction and rearrangement of damaged core and antenna protein complexes in photosystem II (PSII), which led to stronger non-photochemical quenching, lower maximal quantum yield of PSII, and lower adaptation of the photosynthetic apparatus to high light intensity. The observed effects were likely caused by disturbed accumulation and phosphorylation status of main PSII core and antenna proteins. Finally, we found higher accumulation of reactive oxygen species (ROS) in the snrk2.10 mutant leaves under a few-day-long exposure to salinity which also could contribute to the stronger damage of the photosynthetic apparatus and cause other deleterious effects affecting plant growth. We found that the snrk2.4 mutant plants did not display substantial changes in photosynthesis. Overall, our results indicate that SnRK2.10 is activated in leaves shortly after plant exposure to salinity and contributes to salt stress tolerance by maintaining efficient photosynthesis and preventing oxidative damage.

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Section: Discussionmentioning

confidence: 99%

The SnRK2.10 kinase mitigates the adverse effects of salinity by protecting photosynthetic machinery

et al. 2021

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“…The initial step of expressing foreign genes in transgenic plants is a common point of failure due to a myriad of factors relating to gene positional effects ( Pérez-González and Caro, 2019 ) and silencing ( Jackson et al, 2014 ), codon usage ( Nakamura and Sugiura, 2009 ), promotor and terminator combinations ( Beyene et al, 2011 ; de Felippes et al, 2020 ), and potential degradation of the precursor protein ( Lee et al, 2009 ; Shen et al, 2017 ; Hristou et al, 2020 ). This usually requires the analysis of relatively large numbers of plant transformation events and somewhat laborious testing of gene expression cassettes (often in transient expression systems) to ensure appropriate levels of protein expression can be achieved.…”

Section: How Can We Get C I Uptake Systems Into the Chloroplast?mentioning

confidence: 99%

Engineered Accumulation of Bicarbonate in Plant Chloroplasts: Known Knowns and Known Unknowns

et al. 2021

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Heterologous synthesis of a biophysical CO2-concentrating mechanism (CCM) in plant chloroplasts offers significant potential to improve the photosynthetic efficiency of C3 plants and could translate into substantial increases in crop yield. In organisms utilizing a biophysical CCM, this mechanism efficiently surrounds a high turnover rate Rubisco with elevated CO2 concentrations to maximize carboxylation rates. A critical feature of both native biophysical CCMs and one engineered into a C3 plant chloroplast is functional bicarbonate (HCO3−) transporters and vectorial CO2-to-HCO3− converters. Engineering strategies aim to locate these transporters and conversion systems to the C3 chloroplast, enabling elevation of HCO3− concentrations within the chloroplast stroma. Several CCM components have been identified in proteobacteria, cyanobacteria, and microalgae as likely candidates for this approach, yet their successful functional expression in C3 plant chloroplasts remains elusive. Here, we discuss the challenges in expressing and regulating functional HCO3− transporter, and CO2-to-HCO3− converter candidates in chloroplast membranes as an essential step in engineering a biophysical CCM within plant chloroplasts. We highlight the broad technical and physiological concerns which must be considered in proposed engineering strategies, and present our current status of both knowledge and knowledge-gaps which will affect successful engineering outcomes.

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“…Veränderungen im Gleichgewicht zwischen den konkurrierenden Prozessen Vorläuferimport und -degradation können durch posttranslationale Modifi kationen sowie Änderungen der Proteasomaktivität eingeleitet werden. Akkumulierende Vorläufer können Einfl uss auf die Signalprozesse zwischen Plastid und Zellkern nehmen und damit eine Veränderung photosynthetischer Parameter induzieren [9]. Die funktionelle Interaktion von Proteinimport und -abbau ist im unteren Abbildungsteil phänotypisch illustriert.…”

Section: Die Proteasom-vermittelte Vorläuferdegradierung Beeinfl Usst Die Photosyntheseleistungunclassified

“…Die funktionelle Interaktion von Proteinimport und -abbau ist im unteren Abbildungsteil phänotypisch illustriert. Abbildung modifi ziert nach [9].…”

Section: Die Proteasom-vermittelte Vorläuferdegradierung Beeinfl Usst Die Photosyntheseleistungunclassified

“…Daraus lässt sich folgendes Modell ableiten (Abb. 3): Nichtimportierte Vorläuferproteine, die im Cytosol von Importmutanten normalerweise über das 26S-Proteasom abgebaut werden [9], haben in Proteasommutanten eine längere Halbwertszeit. Durch die Vergrößerung des Pools an Vorläufern im Cytosol stehen die Proteine länger für den Import durch eine kompromittierte Importmaschinerie in Mutanten zur Verfügung, was zu deren Translokation in die Plastiden führt.…”

Section: Korrespondenzadresseunclassified

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Safety first: das Ubiquitin-Proteasom-System (UPS) und die Photosynthese

Grimmer

Baginsky

2021

Biospektrum

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The proteasome is essential for the control of protein turnover in the nucleus and the cytosol of eukaryotic cells. Chloroplasts and mitochondria import thousands of nuclear-encoded proteins as precursor proteins from the cytosol. We show that mild genetic proteasome impairment interferes with a cytosolic equilibrium between precursor protein import and degradation resulting in elevated precursor protein abundance in the cytosol and improved photosynthetic performance.

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The Secret Life of Chloroplast Precursor Proteins in the Cytosol

Cited by 7 publications

References 12 publications

The SnRK2.10 kinase mitigates the adverse effects of salinity by protecting photosynthetic machinery

The SnRK2.10 kinase mitigates the adverse effects of salinity by protecting photosynthetic machinery

Engineered Accumulation of Bicarbonate in Plant Chloroplasts: Known Knowns and Known Unknowns

Safety first: das Ubiquitin-Proteasom-System (UPS) und die Photosynthese

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