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Accueil > Départements > Biochimie, Biophysique et Biologie Structurale > Diana KIRILOVSKY : Mécanismes régulateurs chez les organismes photosynthétiques

Publications de l’équipe

2018


  • R. R. Choubeh, E. Wientjes, P. C. Struik, D. Kirilovsky, et H. van Amerongen, « State transitions in the cyanobacterium Synechococcus elongatus 7942 involve reversible quenching of the photosystem II core », Biochimica Et Biophysica Acta, juin 2018.
    Résumé : Cyanobacteria use chlorophyll and phycobiliproteins to harvest light. The resulting excitation energy is delivered to reaction centers (RCs), where photochemistry starts. The relative amounts of excitation energy arriving at the RCs of photosystem I (PSI) and II (PSII) depend on the spectral composition of the light. To balance the excitations in both photosystems, cyanobacteria perform state transitions to equilibrate the excitation energy. They go to state I if PSI is preferentially excited, for example after illumination with blue light (light I), and to state II after illumination with green-orange light (light II) or after dark adaptation. In this study, we performed 77-K time-resolved fluorescence spectroscopy on wild-type Synechococcus elongatus 7942 cells to measure how state transitions affect excitation energy transfer to PSI and PSII in different light conditions and to test the various models that have been proposed in literature. The time-resolved spectra show that the PSII core is quenched in state II and that this is not due to a change in excitation energy transfer from PSII to PSI (spill-over), either direct or indirect via phycobilisomes.
    Mots-clés : B3S, Cyanobacteria, MROP, Photosystem II, State transitions, Time-resolved fluorescence spectroscopy.


  • H. Kubota-Kawai, R. Mutoh, K. Shinmura, P. Sétif, M. M. Nowaczyk, M. Rögner, T. Ikegami, H. Tanaka, et G. Kurisu, « X-ray structure of an asymmetrical trimeric ferredoxin–photosystem I complex », Nature Plants, vol. 4, nᵒ 4, p. 218-224, 2018.

  • M. Messant, S. Timm, A. Fantuzzi, W. Weckwerth, H. Bauwe, B. Rutherford, et A. Krieger-Liszkay, « Glycolate induces redox tuning of photosystem II in vivo: study of a photorespiration mutant », Plant Physiology, mai 2018.
    Résumé : Bicarbonate removal from the non-heme iron at the acceptor side of photosystem II (PSII) was recently shown to shift the midpoint potential of the primary quinone acceptor QA to a more positive potential and lowers the yield of singlet oxygen (1O2) production. The presence of QA- results in weaker binding of bicarbonate, suggesting a redox-based regulatory and protective mechanism where loss of bicarbonate or exchange of bicarbonate by other small carboxylic acids may protect PSII against 1O2 in vivo under photorespiratory conditions. Here we compared the properties of QA in the Arabidopsis (Arabidopsis thaliana) photorespiration mutant hpr1-1, deficient in NADH-dependent, peroxisomal hydroxypyruvate reductase 1 (HPR1), which accumulates glycolate in leaves, to the wild type. Photosynthetic electron transport was affected in the mutant, and chlorophyll fluorescence showed slower electron transport between QA and QB in the mutant. Glycolate induced an increase in the temperature maximum of thermoluminescence emission indicating a shift of the midpoint potential of QA to a more positive value. The yield of 1O2 production was lowered in thylakoid membranes isolated from hpr1-1 compared to the wild type, consistent with a higher potential of QA/QA-. In addition, electron donation to photosystem I was affected in hpr1-1 at higher light intensities consistent with diminished electron transfer out of photosystem II. This study indicates that replacement of bicarbonate at the non-heme iron by a small carboxylate anion occurs in plants in vivo. These findings suggested that replacement of the bicarbonate on the non-heme iron by glycolate may represent a regulatory mechanism that protects PSII against photo-oxidative stress under low CO2 conditions.
    Mots-clés : B3S, MROP.

  • A. Swida-Barteczka, A. Krieger-Liszkay, W. Bilger, U. Voigt, G. Hensel, Z. Szweykowska-Kulinska, et K. Krupinska, « The plastid-nucleus located DNA/RNA binding protein WHIRLY1 regulates microRNA-levels during stress in barley (Hordeum vulgare L.) », RNA biology, juin 2018.
    Résumé : In this article a novel mechanism of retrograde signaling by chloroplasts during stress is described. This mechanism involves the DNA/RNA binding protein WHIRLY1 as a regulator of microRNA levels. By virtue of its dual localization in chloroplasts and the nucleus of the same cell, WHIRLY1 was proposed as an excellent candidate coordinator of chloroplast function and nuclear gene expression. Comparison of wild-type and transgenic plants with an RNAi-mediated knockdown of WHIRLY1 showed, that the transgenic plants were unable to cope with continuous high light conditions. They were impaired in production of several microRNAs mediating post-transcriptional responses during stress. The results support a central role of WHIRLY1 in retrograde signaling and also underpin a so far underestimated role of microRNAs in this process.
    Mots-clés : B3S, MROP, retrograde signaling, small RNA, stress response.

2017


  • P. Cardol et A. Krieger-Liszkay, « From light capture to metabolic needs, oxygenic photosynthesis is an ever-expanding field of study in plants, algae and cyanobacteria », Physiologia Plantarum, mai 2017.
    Résumé : Understanding of the molecular mechanisms of photosynthetic electron and proton transports and their regulation in plants and algae in response to changes in environmental conditions is an important issue for fundamental research on photosynthesis, and may extend even to practical applications by identifying important sites for improvement of photosynthesis. The significance and often centrality of regulatory mechanisms of photosynthetic electron transport is well established for processes in plant acclimation. In recent years, significant advancements have been achieved in understanding of regulatory processes such as dissipation of excess energy in the antenna systems, state transitions, cyclic electron flow, oxygen reduction by flavodiiron enzymes and many others.
    Mots-clés : B3S, MROP.


  • K. Feilke, G. Ajlani, et A. Krieger-Liszkay, « Correction to ‘Overexpression of plastid terminal oxidase in <i>Synechocystis</i> sp. PCC 6803 alters cellular redox state’ », Philosophical Transactions of the Royal Society B: Biological Sciences, vol. 372, nᵒ 1736, p. 20170277, déc. 2017.

  • K. Feilke, G. Ajlani, et A. Krieger-Liszkay, « Overexpression of plastid terminal oxidase in Synechocystis sp. PCC 6803 alters cellular redox state », Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, vol. 372, nᵒ 1730, sept. 2017.
    Résumé : Cyanobacteria are the most ancient organisms performing oxygenic photosynthesis, and they are the ancestors of plant plastids. All plastids contain the plastid terminal oxidase (PTOX), while only certain cyanobacteria contain PTOX. Many putative functions have been discussed for PTOX in higher plants including a photoprotective role during abiotic stresses like high light, salinity and extreme temperatures. Since PTOX oxidizes PQH2 and reduces oxygen to water, it is thought to protect against photo-oxidative damage by removing excess electrons from the plastoquinone (PQ) pool. To investigate the role of PTOX we overexpressed rice PTOX fused to the maltose-binding protein (MBP-OsPTOX) in Synechocystis sp. PCC 6803, a model cyanobacterium that does not encode PTOX. The fusion was highly expressed and OsPTOX was active, as shown by chlorophyll fluorescence and P700 absorption measurements. The presence of PTOX led to a highly oxidized state of the NAD(P)H/NAD(P)(+) pool, as detected by NAD(P)H fluorescence. Moreover, in the PTOX overexpressor the electron transport capacity of PSI relative to PSII was higher, indicating an alteration of the photosystem I (PSI) to photosystem II (PSII) stoichiometry. We suggest that PTOX controls the expression of responsive genes of the photosynthetic apparatus in a different way from the PQ/PQH2 ratio.This article is part of the themed issue 'Enhancing photosynthesis in crop plants: targets for improvement'.
    Mots-clés : B3S, cellular redox state, chlorophyll fluorescence, LBMS, MROP, NAD(P)H fluorescence, P700 absorption, plastid terminal oxidase, Synechocystis sp. PCC 6803.

  • M. Loussouarn, A. Krieger-Liszkay, L. Svilar, A. Bily, S. Birtic, et M. Havaux, « Carnosic acid and carnosol, two major antioxidants of rosemary, act through different mechanisms », Plant Physiology, sept. 2017.
    Résumé : Carnosic acid, a phenolic diterpene specific of the Lamiaceae family, is highly abundant in rosemary species. Despite numerous industrial and medicinal/pharmaceutical applications of its antioxidative features, this compound in planta and its antioxidant mechanism have received little attention, except a few studies of rosemary plants under natural conditions. In vitro analyses, using HPLC-UV and luminescence imaging, revealed that carnosic acid and its major oxidized derivative, carnosol, protect lipids from oxidation. Both compounds preserved linolenic acid and monogalactosyldiacylglycerol from singlet oxygen and from hydroxyl radical. When applied exogenously, they were both able to protect thylakoid membranes prepared from Arabidopsis leaves against lipid peroxidation. Different levels of carnosic acid and carnosol in two contrasted rosemary varieties correlated with tolerance to lipid peroxidation. Upon ROS oxidation of lipids, carnosic acid was consumed and oxidized into various derivatives, including into carnosol, while carnosol resisted, suggesting that carnosic acid is a chemical quencher of ROS. The antioxidative function of carnosol relies on another mechanism, occurring directly in lipid oxidation process. Under oxidative conditions that did not involve ROS generation, carnosol inhibited lipid peroxidation, contrary to carnosic acid. Using spin probes and EPR detection, we confirmed that carnosic acid, rather than carnosol, is a ROS quencher. Various oxidized derivatives of carnosic acid were detected in rosemary leaves in low light, indicating chronic oxidation of this compound, and accumulated in plants exposed to stress conditions, in parallel with a loss of carnosic acid, confirming that chemical quenching of ROS by carnosic acid takes place in planta.
    Mots-clés : B3S, MROP.


  • C. Mignée, R. Mutoh, A. Krieger-Liszkay, G. Kurisu, et P. Sétif, « Gallium ferredoxin as a tool to study the effects of ferredoxin binding to photosystem I without ferredoxin reduction », Photosynthesis Research, févr. 2017.

  • F. Muzzopappa, A. Wilson, V. Yogarajah, S. Cot, F. Perreau, C. Montigny, C. Bourcier de Carbon, et D. Kirilovsky, « The paralogs to the C-terminal domain of the cyanobacterial OCP are carotenoid donors to HCPs », Plant Physiology, sept. 2017.
    Résumé : The photoactive Orange Carotenoid Protein photoprotects cyanobacteria cells by quenching singlet oxygen and excess excitation energy. Its N-terminal domain (NTD) is the active part of the protein and the C-terminal domain (CTD) regulates the activity. Recently, the characteristics of a family of soluble carotenoid-binding proteins (Helical Carotenoid Proteins or HCPs), paralogs of NTD-OCP, were described. Bioinformatics studies also revealed the existence of genes coding for homologs of CTD. Here, we show that the latter genes encode carotenoid proteins (CTDHs). This family of proteins contains two subgroups with distinct characteristics. One CTDH of each clade was further characterized and proved to be very good singlet oxygen quenchers. When synthesized in E. coli or Synechocystis PCC 6803, CTDHs form dimers that share a carotenoid molecule and are able to transfer their carotenoid to apo-HCPs and apo-OCP. The CTDHs from clade 2 have a cysteine in position 103. A disulfide bond is easily formed between the monomers of the dimer preventing carotenoid transfer. This suggests that the transfer of the carotenoid could be redox regulated in clade 2 CTDH. We also demonstrate here that apo-OCPs and apo CTDHs are able to take the carotenoid directly from membranes, while HCPs are unable. HCPs need the presence of CTDH to become holo-proteins. We propose that in cyanobacteria the CTDHs are carotenoid donors to HCPs.
    Mots-clés : B3S, LPSM, MROP.


  • P. Pétriacq, L. de Bont, L. Genestout, J. Hao, C. Laureau, I. Florez-Sarasa, T. Rzigui, G. Queval, F. Gilard, C. Mauve, F. Guérard, M. Lamothe-Sibold, J. Marion, C. Fresneau, S. Brown, A. Danon, A. Krieger-Liszkay, R. Berthomé, M. Ribas-Carbo, G. Tcherkez, G. Cornic, B. Pineau, B. Gakière, et R. De Paepe, « Photoperiod Affects the Phenotype of Mitochondrial Complex I Mutants », Plant Physiology, vol. 173, nᵒ 1, p. 434-455, 2017.
    Mots-clés : B3S, BIOCELL, DYNBSJ, IMAGIF, MROP, PF, PHOT.


  • T. Roach, T. Baur, W. Stöggl, et A. Krieger-Liszkay, « Chlamydomonas reinhardtii responding to high light: A role for 2-propenal (acrolein) », Physiologia Plantarum, 2017.

  • Á. Sánchez-Corrionero, I. Sánchez-Vicente, S. González-Pérez, A. Corrales, A. Krieger-Liszkay, Ó. Lorenzo, et J. B. Arellano, « Singlet oxygen triggers chloroplast rupture and cell death in the zeaxanthin epoxidase defective mutant aba1 of Arabidopsis thaliana under high light stress », Journal of Plant Physiology, vol. 216, p. 188-196, juill. 2017.
    Résumé : The two Arabidopsis thaliana mutants, aba1 and max4, were previously identified as sharing a number of co-regulated genes with both the flu mutant and Arabidopsis cell suspension cultures exposed to high light (HL). On this basis, we investigated whether aba1 and max4 were generating high amounts of singlet oxygen ((1)O2) and activating (1)O2-mediated cell death. Thylakoids of aba1 produced twice as much (1)O2 as thylakoids of max4 and wild type (WT) plants when illuminated with strong red light. (1)O2 was measured using the spin probe 2,2,6,6-tetramethyl-4-piperidone hydrochloride. 77-K chlorophyll fluorescence emission spectra of thylakoids revealed lower aggregation of the light harvesting complex II in aba1. This was rationalized as a loss of connectivity between photosystem II (PSII) units and as the main cause for the high yield of (1)O2 generation in aba1. Up-regulation of the (1)O2 responsive gene AAA-ATPase was only observed with statistical significant in aba1 under HL. Two early jasmonate (JA)-responsive genes, JAZ1 and JAZ5, encoding for two repressor proteins involved in the negative feedback regulation of JA signalling, were not up-regulated to the WT plant levels. Chloroplast aggregation followed by chloroplast rupture and eventual cell death was observed by confocal imaging of the fluorescence emission of leaf cells of transgenic aba1 plants expressing the chimeric fusion protein SSU-GFP. Cell death was not associated with direct (1)O2 cytotoxicity in aba1, but rather with a delayed stress response. In contrast, max4 did not show evidence of (1)O2-mediated cell death. In conclusion, aba1 may serve as an alternative model to other (1)O2-overproducing mutants of Arabidopsis for investigating (1)O2-mediated cell death.
    Mots-clés : AAA-ATPase, aba1, B3S, Cell Death, Chloroplast rupture, JAZ repressors, MROP, Singlet oxygen.

  • P. Sétif, R. Mutoh, et G. Kurisu, « Dynamics and energetics of cyanobacterial photosystem I:ferredoxin complexes in different redox states », Biochimica Et Biophysica Acta, avr. 2017.
    Résumé : Fast turnover of ferredoxin/Fd reduction by photosystem-I/PSI requires that it dissociates rapidly after it has been reduced by PSI:Fd intracomplex electron transfer. The rate constants of Fd dissociation from PSI have been determined by flash-absorption spectroscopy with different combinations of cyanobacterial PSIs and Fds, and different redox states of Fd and of the terminal PSI acceptor (FAFB). Newly obtained values were derived firstly from the fact that the dissociation constant between PSI and redox-inactive gallium-substituted Fd increases upon (FAFB) reduction and secondly from the characterization and elucidation of a kinetic phase following intracomplex Fd reduction to binding of oxidized Fd to PSI, a process which is rate-limited by the foregoing dissociation of reduced Fd from PSI. By reference to the complex with oxidized partners, dissociation rate constants were found to increase moderately with (FAFB) single reduction and by about one order of magnitude after electron transfer from (FAFB)(-) to Fd, therefore favoring turnover of Fd reduction by PSI. With Thermosynechococcus elongatus partners, values of 270, 730 and >10000 s(-1) were thus determined for (FAFB)Fdoxidized, (FAFB)(-)Fdoxidized and (FAFB)Fdreduced, respectively. Moreover, assuming a conservative upper limit for the association rate constant between reduced Fd and PSI, a significant negative shift of the Fd midpoint potential upon binding to PSI has been calculated (<-60 mV for Thermosynechococcus elongatus). From the present state of knowledge, the question is still open whether this redox shift is compatible with a large (>10) equilibrium constant for intracomplex reduction of Fd from (FAFB)(-).
    Mots-clés : association and dissociation kinetics, B3S, binding-induced shift of midpoint potential, Electron transfer, ferredoxin binding, gallium-substituted ferredoxin, MROP, photosynthesis, redox potential.

  • V. Šlouf, V. Kuznetsova, M. Fuciman, C. B. de Carbon, A. Wilson, D. Kirilovsky, et T. Polívka, « Ultrafast spectroscopy tracks carotenoid configurations in the orange and red carotenoid proteins from cyanobacteria », Photosynthesis Research, vol. 131, nᵒ 1, p. 105-117, janv. 2017.
    Résumé : A quenching mechanism mediated by the orange carotenoid protein (OCP) is one of the ways cyanobacteria protect themselves against photooxidative stress. Here, we present a femtosecond spectroscopic study comparing OCP and RCP (red carotenoid protein) samples binding different carotenoids. We confirmed significant changes in carotenoid configuration upon OCP activation reported by Leverenz et al. (Science 348:1463-1466. doi: 10.1126/science.aaa7234 , 2015) by comparing the transient spectra of OCP and RCP. The most important marker of these changes was the magnitude of the transient signal associated with the carotenoid intramolecular charge-transfer (ICT) state. While OCP with canthaxanthin exhibited a weak ICT signal, it increased significantly for canthaxanthin bound to RCP. On the contrary, a strong ICT signal was recorded in OCP binding echinenone excited at the red edge of the absorption spectrum. Because the carbonyl oxygen responsible for the appearance of the ICT signal is located at the end rings of both carotenoids, the magnitude of the ICT signal can be used to estimate the torsion angles of the end rings. Application of two different excitation wavelengths to study OCP demonstrated that the OCP sample contains two spectroscopically distinct populations, none of which is corresponding to the photoactivated product of OCP.
    Mots-clés : B3S, Carotenoids, Cyanobacteria, Intramolecular charge-transfer state, MROP, Non-photochemical quenching, Orange carotenoid protein, Red carotenoid protein, Spectrum Analysis, Ultrafast spectroscopy.


  • A. Thurotte, C. Bourcier de Carbon, A. Wilson, L. Talbot, S. Cot, R. López-Igual, et D. Kirilovsky, « The cyanobacterial Fluorescence Recovery Protein has two distinct activities: Orange Carotenoid Protein amino acids involved in FRP interaction », Biochimica et Biophysica Acta (BBA) - Bioenergetics, vol. 1858, nᵒ 4, p. 308-317, 2017.

2016


  • A. M. Acuña, R. Kaňa, M. Gwizdala, J. J. Snellenburg, P. van Alphen, B. van Oort, D. Kirilovsky, R. van Grondelle, et I. H. M. van Stokkum, « A method to decompose spectral changes in Synechocystis PCC 6803 during light-induced state transitions », Photosynthesis Research, vol. 130, nᵒ 1-3, p. 237-249, déc. 2016.
    Résumé : Cyanobacteria have developed responses to maintain the balance between the energy absorbed and the energy used in different pigment-protein complexes. One of the relatively rapid (a few minutes) responses is activated when the cells are exposed to high light intensities. This mechanism thermally dissipates excitation energy at the level of the phycobilisome (PB) antenna before it reaches the reaction center. When exposed to low intensities of light that modify the redox state of the plastoquinone pool, the so-called state transitions redistribute energy between photosystem I and II. Experimental techniques to investigate the underlying mechanisms of these responses, such as pulse-amplitude modulated fluorometry, are based on spectrally integrated signals. Previously, a spectrally resolved fluorometry method has been introduced to preserve spectral information. The analysis method introduced in this work allows to interpret SRF data in terms of species-associated spectra of open/closed reaction centers (RCs), (un)quenched PB and state 1 versus state 2. Thus, spectral differences in the time-dependent fluorescence signature of photosynthetic organisms under varying light conditions can be traced and assigned to functional emitting species leading to a number of interpretations of their molecular origins. In particular, we present evidence that state 1 and state 2 correspond to different states of the PB-PSII-PSI megacomplex.
    Mots-clés : B3S, Cyanobacteria, MROP, Singular value decomposition, Spectrally resolved fluorometry, Time-resolved spectroscopy.

  • A. M. Acuña, J. J. Snellenburg, M. Gwizdala, D. Kirilovsky, R. van Grondelle, et I. H. M. van Stokkum, « Resolving the contribution of the uncoupled phycobilisomes to cyanobacterial pulse-amplitude modulated (PAM) fluorometry signals », Photosynthesis Research, vol. 127, nᵒ 1, p. 91-102, janv. 2016.
    Résumé : Pulse-amplitude modulated (PAM) fluorometry is extensively used to characterize photosynthetic organisms on the slow time-scale (1-1000 s). The saturation pulse method allows determination of the quantum yields of maximal (F(M)) and minimal fluorescence (F(0)), parameters related to the activity of the photosynthetic apparatus. Also, when the sample undergoes a certain light treatment during the measurement, the fluorescence quantum yields of the unquenched and the quenched states can be determined. In the case of cyanobacteria, however, the recorded fluorescence does not exclusively stem from the chlorophyll a in photosystem II (PSII). The phycobilins, the pigments of the cyanobacterial light-harvesting complexes, the phycobilisomes (PB), also contribute to the PAM signal, and therefore, F(0) and F(M) are no longer related to PSII only. We present a functional model that takes into account the presence of several fluorescent species whose concentrations can be resolved provided their fluorescence quantum yields are known. Data analysis of PAM measurements on in vivo cells of our model organism Synechocystis PCC6803 is discussed. Three different components are found necessary to fit the data: uncoupled PB (PB(free)), PB-PSII complexes, and free PSI. The free PSII contribution was negligible. The PB(free) contribution substantially increased in the mutants that lack the core terminal emitter subunits allophycocyanin D or allophycocyanin F. A positive correlation was found between the amount of PB(free) and the rate constants describing the binding of the activated orange carotenoid protein to PB, responsible for non-photochemical quenching.
    Mots-clés : B3S, Computer Simulation, Cyanobacteria, Fluorescence, Fluorescence quantum yield, Fluorometry, Models, Biological, MROP, Mutation, Non-photochemical quenching, Photosystem I Protein Complex, Photosystem II Protein Complex, Phycobilisome, Phycobilisomes, Phycocyanin, Protein Subunits, Pulse-amplitude modulated (PAM) fluorometry, Synechocystis, Time Factors.


  • C. Biniek, E. Heyno, J. Kruk, F. Sparla, P. Trost, et A. Krieger-Liszkay, « Role of the NAD(P)H quinone oxidoreductase NQR and the cytochrome b AIR12 in controlling superoxide generation at the plasma membrane », Planta, déc. 2016.

  • K. Brinkert, S. De Causmaecker, A. Krieger-Liszkay, A. Fantuzzi, et A. W. Rutherford, « Bicarbonate-induced redox tuning in Photosystem II for regulation and protection », Proceedings of the National Academy of Sciences of the United States of America, vol. 113, nᵒ 43, p. 12144-12149, oct. 2016.
    Résumé : The midpoint potential (Em) of [Formula: see text], the one-electron acceptor quinone of Photosystem II (PSII), provides the thermodynamic reference for calibrating PSII bioenergetics. Uncertainty exists in the literature, with two values differing by ∼80 mV. Here, we have resolved this discrepancy by using spectroelectrochemistry on plant PSII-enriched membranes. Removal of bicarbonate (HCO3(-)) shifts the Em from ∼-145 mV to -70 mV. The higher values reported earlier are attributed to the loss of HCO3(-) during the titrations (pH 6.5, stirred under argon gassing). These findings mean that HCO3(-) binds less strongly when QA(-•) is present. Light-induced QA(-•) formation triggered HCO3(-) loss as manifest by the slowed electron transfer and the upshift in the Em of QA HCO3(-)-depleted PSII also showed diminished light-induced (1)O2 formation. This finding is consistent with a model in which the increase in the Em of [Formula: see text] promotes safe, direct [Formula: see text] charge recombination at the expense of the damaging back-reaction route that involves chlorophyll triplet-mediated (1)O2 formation [Johnson GN, et al. (1995) Biochim Biophys Acta 1229:202-207]. These findings provide a redox tuning mechanism, in which the interdependence of the redox state of QA and the binding by HCO3(-) regulates and protects PSII. The potential for a sink (CO2) to source (PSII) feedback mechanism is discussed.
    Mots-clés : B3S, CO2 fixation, MROP, photoassembly, photoinhibition, photosynthesis, water oxidation.


  • Q. Bruggeman, C. Mazubert, F. Prunier, R. Lugan, K. X. Chan, S. Y. Phua, B. J. Pogson, A. Krieger-Liszkay, M. Delarue, M. Benhamed, C. Bergounioux, et C. Raynaud, « Chloroplasts activity and PAP-signaling regulate programmed cell death in Arabidopsis », Plant Physiology, p. pp.01872.2015, janv. 2016.


  • K. - J. Dietz, I. Turkan, et A. Krieger-Liszkay, « Redox- and Reactive Oxygen Species-Dependent Signaling into and out of the Photosynthesizing Chloroplast », Plant Physiology, vol. 171, nᵒ 3, p. 1541-1550, 2016.

  • K. Feilke, P. Streb, G. Cornic, F. Perreau, J. Kruk, et A. Krieger-Liszkay, « Effect of Chlamydomonas plastid terminal oxidase 1 expressed in tobacco on photosynthetic electron transfer », The Plant Journal: For Cell and Molecular Biology, vol. 85, nᵒ 2, p. 219-228, janv. 2016.
    Résumé : The plastid terminal oxidase PTOX is a plastohydroquinone:oxygen oxidoreductase that is important for carotenoid biosynthesis and plastid development. Its role in photosynthesis is controversially discussed. Under a number of abiotic stress conditions, the protein level of PTOX increases. PTOX is thought to act as a safety valve under high light protecting the photosynthetic apparatus against photodamage. However, transformants with high PTOX level were reported to suffer from photoinhibition. To analyze the effect of PTOX on the photosynthetic electron transport, tobacco expressing PTOX-1 from Chlamydomonas reinhardtii (Cr-PTOX1) was studied by chlorophyll fluorescence, thermoluminescence, P700 absorption kinetics and CO2 assimilation. Cr-PTOX1 was shown to compete very efficiently with the photosynthetic electron transport for PQH2 . High pressure liquid chromatography (HPLC) analysis confirmed that the PQ pool was highly oxidized in the transformant. Immunoblots showed that, in the wild-type, PTOX was associated with the thylakoid membrane only at a relatively alkaline pH value while it was detached from the membrane at neutral pH. We present a model proposing that PTOX associates with the membrane and oxidizes PQH2 only when the oxidation of PQH2 by the cytochrome b6 f complex is limiting forward electron transport due to a high proton gradient across the thylakoid membrane.
    Mots-clés : B3S, Chlamydomonas, Chlamydomonas reinhardtii PTOX1, Electron Transport, MROP, Nicotiana tabacum, Oxidoreductases, photooxidative stress, photosynthesis, photosynthetic electron transport, Plants, Genetically Modified, plastid terminal oxidase, Plastids, regulation, Tobacco.


  • M. Gwizdala, R. Berera, D. Kirilovsky, R. van Grondelle, et T. P. J. Krüger, « Controlling Light Harvesting with Light », Journal of the American Chemical Society, vol. 138, nᵒ 36, p. 11616-11622, sept. 2016.


  • D. Harris, O. Tal, D. Jallet, A. Wilson, D. Kirilovsky, et N. Adir, « Orange carotenoid protein burrows into the phycobilisome to provide photoprotection », Proceedings of the National Academy of Sciences, vol. 113, nᵒ 12, p. E1655-E1662, mars 2016.


  • D. Kirilovsky et C. A. Kerfeld, « Cyanobacterial photoprotection by the orange carotenoid protein », Nature Plants, vol. 2, nᵒ 12, p. 16180, déc. 2016.


  • A. Krieger-Liszkay et K. Feilke, « The Dual Role of the Plastid Terminal Oxidase PTOX: Between a Protective and a Pro-oxidant Function », Frontiers in Plant Science, vol. 6, janv. 2016.


  • R. López-Igual, A. Wilson, R. L. Leverenz, M. R. Melnicki, C. Bourcier de Carbon, M. Sutter, A. Turmo, F. Perreau, C. A. Kerfeld, et D. Kirilovsky, « Different Functions of the Paralogs to the N-Terminal Domain of the Orange Carotenoid Protein in the Cyanobacterium Anabaena sp. PCC 7120 », Plant Physiology, vol. 171, nᵒ 3, p. 1852-1866, 2016.


  • M.  R. Melnicki, R.  L. Leverenz, M. Sutter, R. López-Igual, A. Wilson, E.  G. Pawlowski, F. Perreau, D. Kirilovsky, et C.  A. Kerfeld, « Structure, Diversity, and Evolution of a New Family of Soluble Carotenoid-Binding Proteins in Cyanobacteria », Molecular Plant, vol. 9, nᵒ 10, p. 1379-1394, 2016.


  • B. Naranjo, C. Mignée, A. Krieger-Liszkay, D. Hornero-Méndez, L. Gallardo-Guerrero, F. J. Cejudo, et M. Lindahl, « The chloroplast NADPH thioredoxin reductase C, NTRC, controls non-photochemical quenching of light energy and photosynthetic electron transport in <i>Arabidopsis</i>: NTRC controls photosynthetic electron transport », Plant, Cell & Environment, vol. 39, nᵒ 4, p. 804-822, 2016.


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2015

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