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Virtanen O, Tyystjärvi E. Plastoquinone pool redox state and control of state transitions in Chlamydomonas reinhardtii in darkness and under illumination. Photosynth Res 2023; 155:59-76. [PMID: 36282464 PMCID: PMC9792418 DOI: 10.1007/s11120-022-00970-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 09/26/2022] [Indexed: 06/16/2023]
Abstract
Movement of LHCII between two photosystems has been assumed to be similarly controlled by the redox state of the plastoquinone pool (PQ-pool) in plants and green algae. Here we show that the redox state of the PQ-pool of Chlamydomonas reinhardtii can be determined with HPLC and use this method to compare the light state in C. reinhardtii with the PQ-pool redox state in a number of conditions. The PQ-pool was at least moderately reduced under illumination with all tested types of visible light and oxidation was achieved only with aerobic dark treatment or with far-red light. Although dark incubations and white light forms with spectral distribution favoring one photosystem affected the redox state of PQ-pool differently, they induced similar Stt7-dependent state transitions. Thus, under illumination the dynamics of the PQ-pool and its connection with light state appears more complicated in C. reinhardtii than in plants. We suggest this to stem from the larger number of LHC-units and from less different absorption profiles of the photosystems in C. reinhardtii than in plants. The data demonstrate that the two different control mechanisms required to fulfill the dual function of state transitions in C. reinhardtii in photoprotection and in balancing light utilization are activated via different means.
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Affiliation(s)
- Olli Virtanen
- Department of Life Technologies/Molecular Plant Biology, University of Turku, 20014, Turku, Finland
| | - Esa Tyystjärvi
- Department of Life Technologies/Molecular Plant Biology, University of Turku, 20014, Turku, Finland.
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2
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Patil PP, Mohammad Aslam S, Vass I, Szabó M. Characterization of the wave phenomenon of flash-induced chlorophyll fluorescence in Chlamydomonas reinhardtii. Photosynth Res 2022; 152:235-244. [PMID: 35166999 PMCID: PMC9424139 DOI: 10.1007/s11120-022-00900-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 01/25/2022] [Indexed: 06/01/2023]
Abstract
Flash-induced chlorophyll fluorescence relaxation is a powerful tool to monitor the reoxidation reactions of the reduced primary quinone acceptor, QA- by QB and the plastoquinone (PQ) pool, as well as the charge recombination reactions between the donor and acceptor side components of Photosystem II (PSII). Under certain conditions, when the PQ pool is highly reduced (e.g. in microaerobic conditions), a wave phenomenon appears in the fluorescence relaxation kinetics, which reflects the transient reoxidation and re-reduction of QA- by various electron transfer processes, which in cyanobacteria is mediated by NAD(P)H dehydrogenase (NDH-1). The wave phenomenon was also observed and assigned to the operation of type 2 NAD(P)H dehydrogenase (NDH-2) in the green alga Chlamydomonas reinhardtii under hydrogen-producing conditions, which required a long incubation of algae under sulphur deprivation (Krishna et al. J Exp Bot 70 (21):6321-6336, 2019). However, the conditions that induce the wave remained largely uncharacterized so far in microalgae. In this work, we investigated the wave phenomenon in Chlamydomonas reinhardtii under conditions that lead to a decrease of PSII activity by applying hydroxylamine treatment, which impacts the donor side of PSII in combination with a strongly reducing environment of the PQ pool (microaerobic conditions). A similar wave phenomenon could be induced by photoinhibitory conditions (illumination with strong light in the presence of the protein synthesis inhibitor lincomycin). These results indicate that the fluorescence wave phenomenon is activated in green algae when the PSII activity decreases relative to Photosystem I (PS I) activity and the PQ pool is strongly reduced. Therefore, the fluorescence wave could be used as a sensitive indicator of altered intersystem electron transfer processes, e.g. under stress conditions.
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Affiliation(s)
- Priyanka Pradeep Patil
- Biological Research Centre, Institute of Plant Biology, Eötvös Loránd Research Network (ELKH), Szeged, Hungary
| | - Sabit Mohammad Aslam
- Biological Research Centre, Institute of Plant Biology, Eötvös Loránd Research Network (ELKH), Szeged, Hungary
- Doctoral School of Biology, University of Szeged, Szeged, Hungary
| | - Imre Vass
- Biological Research Centre, Institute of Plant Biology, Eötvös Loránd Research Network (ELKH), Szeged, Hungary.
| | - Milán Szabó
- Biological Research Centre, Institute of Plant Biology, Eötvös Loránd Research Network (ELKH), Szeged, Hungary.
- Climate Change Cluster, University of Technology Sydney, Ultimo, Australia.
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3
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Vilyanen D, Naydov I, Ivanov B, Borisova-Mubarakshina M, Kozuleva M. Inhibition of plastoquinol oxidation at the cytochrome b 6f complex by dinitrophenyl ether of iodonitrothymol (DNP-INT) depends on irradiance and H + uptake by thylakoid membranes. Biochim Biophys Acta Bioenerg 2022; 1863:148506. [PMID: 34751144 DOI: 10.1016/j.bbabio.2021.148506] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 10/08/2021] [Accepted: 10/19/2021] [Indexed: 11/26/2022]
Abstract
Inhibitory analysis is a useful tool for studying reactions in the photosynthetic apparatus. After introducing by Aachim Trebst in 1978, dinitrophenylether of iodonitrothymol (DNP-INT), a competitive inhibitor of plastoquinol oxidation at the cytochrome (cyt.) b6f complex, has been widely applied to study reactions occurring in the plastoquinone pool and the cyt. b6f complex. Here we examine the inhibitory efficiency of DNP-INT by implementing three approaches to estimate the extent of blockage of electron flow from the plastoquinone pool to photosystem I in isolated thylakoids from spinach (Spinacia oleracea). We confirm that DNP-INT is a potent inhibitor of electron flow to photosystem I and demonstrate that inhibitory action of DNP-INT depends on irradiance and H+ uptake by thylakoid membranes. Based on these findings, we infer that affinity of the quinol-oxidizing site of the cyt. b6f complex to DNP-INT is increased in the light due to hydrogen bonding between DNP-INT molecules and acidic amino acid residue(s), which is (are) protonated in the light.
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Affiliation(s)
- Daria Vilyanen
- Institute of Basic Biological Problems of the Russian Academy of Sciences, Federal Research Center, Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Pushchino, Russia
| | - Ilya Naydov
- Institute of Basic Biological Problems of the Russian Academy of Sciences, Federal Research Center, Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Pushchino, Russia
| | - Boris Ivanov
- Institute of Basic Biological Problems of the Russian Academy of Sciences, Federal Research Center, Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Pushchino, Russia
| | - Maria Borisova-Mubarakshina
- Institute of Basic Biological Problems of the Russian Academy of Sciences, Federal Research Center, Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Pushchino, Russia
| | - Marina Kozuleva
- Institute of Basic Biological Problems of the Russian Academy of Sciences, Federal Research Center, Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Pushchino, Russia.
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4
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Messant M, Shimakawa G, Perreau F, Miyake C, Krieger-Liszkay A. Evolutive differentiation between alga- and plant-type plastid terminal oxidase: Study of plastid terminal oxidase PTOX isoforms in Marchantia polymorpha. Biochim Biophys Acta Bioenerg 2020; 1862:148309. [PMID: 32956677 DOI: 10.1016/j.bbabio.2020.148309] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 09/02/2020] [Accepted: 09/14/2020] [Indexed: 10/23/2022]
Abstract
The liverwort Marchantia polymorpha contains two isoforms of the plastid terminal oxidase (PTOX), an enzyme that catalyzes the reduction of oxygen to water using plastoquinol as substrate. Phylogenetic analyses showed that one isoform, here called MpPTOXa, is closely related to isoforms occurring in plants and some algae, while the other isoform, here called MpPTOXb, is closely related to the two isoforms occurring in Chlamydomonas reinhardtii. Mutants of each isoform were created in Marchantia polymorpha using CRISPR/Cas9 technology. While no obvious phenotype was found for these mutants, chlorophyll fluorescence analyses demonstrated that the plastoquinone pool was in a higher reduction state in both mutants. This was visible at the level of fluorescence measured in dark-adapted material and by post illumination fluorescence rise. These results suggest that both isoforms have a redundant function. However, when P700 oxidation and re-reduction was studied, differences between these two isoforms were observed. Furthermore, the mutant affected in MpPTOXb showed a slight alteration in the pigment composition, a higher non-photochemical quenching and a slightly lower electron transport rate through photosystem II. These differences may be explained either by differences in the enzymatic activities or by different activities attributed to preferential involvement of the two PTOX isoforms to either linear or cyclic electron flow.
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Affiliation(s)
- Marine Messant
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, 91198 Gif-sur-Yvette cedex, France
| | - Ginga Shimakawa
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, 91198 Gif-sur-Yvette cedex, France
| | - François Perreau
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université Paris-Saclay, 78000 Versailles, France
| | - Chikahiro Miyake
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
| | - Anja Krieger-Liszkay
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, 91198 Gif-sur-Yvette cedex, France.
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Gómez R, Figueroa N, Melzer M, Hajirezaei MR, Carrillo N, Lodeyro AF. Photosynthetic characterization of flavodoxin-expressing tobacco plants reveals a high light acclimation-like phenotype. Biochim Biophys Acta Bioenerg 2020; 1861:148211. [PMID: 32315624 DOI: 10.1016/j.bbabio.2020.148211] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 03/17/2020] [Accepted: 04/14/2020] [Indexed: 01/15/2023]
Abstract
Flavodoxins are electron carrier flavoproteins present in bacteria and photosynthetic microorganisms which duplicate the functional properties of iron-sulphur containing ferredoxins and replace them under adverse environmental situations that lead to ferredoxin decline. When expressed in plant chloroplasts, flavodoxin complemented ferredoxin deficiency and improved tolerance to multiple sources of biotic, abiotic and xenobiotic stress. Analysis of flavodoxin-expressing plants grown under normal conditions, in which the two carriers are present, revealed phenotypic effects unrelated to ferredoxin replacement. Flavodoxin thus provided a tool to alter the chloroplast redox poise in a customized way and to investigate its consequences on plant physiology and development. We describe herein the effects exerted by the flavoprotein on the function of the photosynthetic machinery. Pigment analysis revealed significant increases in chlorophyll a, carotenoids and chlorophyll a/b ratio in flavodoxin-expressing tobacco lines. Results suggest smaller antenna size in these plants, supported by lower relative contents of light-harvesting complex proteins. Chlorophyll a fluorescence and P700 spectroscopy measurements indicated that transgenic plants displayed higher quantum yields for both photosystems, a more oxidized plastoquinone pool under steady-state conditions and faster plastoquinone dark oxidation after a pulse of saturating light. Many of these effects resemble the phenotypes exhibited by leaves adapted to high irradiation, a most common environmental hardship faced by plants growing in the field. The results suggest that flavodoxin-expressing plants would be better prepared to cope with this adverse situation, and concur with earlier observations reporting that hundreds of stress-responsive genes were induced in the absence of stress in these lines.
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Affiliation(s)
- Rodrigo Gómez
- Instituto de Biología Molecular y Celular de Rosario (IBR-UNR/CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), 2000 Rosario, Argentina
| | - Nicolás Figueroa
- Instituto de Biología Molecular y Celular de Rosario (IBR-UNR/CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), 2000 Rosario, Argentina
| | - Michael Melzer
- Leibniz Institute of Plant Genetics and Crop Plant Research, OT Gatersleben, Corrensstrasse 3, D-06466 Stadt Seeland, Germany
| | - Mohammad-Reza Hajirezaei
- Leibniz Institute of Plant Genetics and Crop Plant Research, OT Gatersleben, Corrensstrasse 3, D-06466 Stadt Seeland, Germany
| | - Néstor Carrillo
- Instituto de Biología Molecular y Celular de Rosario (IBR-UNR/CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), 2000 Rosario, Argentina
| | - Anabella F Lodeyro
- Instituto de Biología Molecular y Celular de Rosario (IBR-UNR/CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), 2000 Rosario, Argentina.
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Acuña AM, van Alphen P, Branco Dos Santos F, van Grondelle R, Hellingwerf KJ, van Stokkum IHM. Spectrally decomposed dark-to-light transitions in Synechocystis sp. PCC 6803. Photosynth Res 2018; 137:307-320. [PMID: 29600442 DOI: 10.1007/s11120-018-0505-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 03/23/2018] [Indexed: 06/08/2023]
Abstract
Photosynthetic activity and respiration share the thylakoid membrane in cyanobacteria. We present a series of spectrally resolved fluorescence experiments where whole cells of the cyanobacterium Synechocystis sp. PCC 6803 and mutants thereof underwent a dark-to-light transition after different dark-adaptation (DA) periods. Two mutants were used: (i) a PSI-lacking mutant (ΔPSI) and (ii) M55, a mutant without NAD(P)H dehydrogenase type-1 (NDH-1). For comparison, measurements of the wild-type were also carried out. We recorded spectrally resolved fluorescence traces over several minutes with 100 ms time resolution. The excitation light was at 590 nm so as to specifically excite the phycobilisomes. In ΔPSI, DA time has no influence, and in dichlorophenyl-dimethylurea (DCMU)-treated samples we identify three main fluorescent components: PB-PSII complexes with closed (saturated) RCs, a quenched or open PB-PSII complex, and a PB-PSII 'not fully closed.' For the PSI-containing organisms without DCMU, we conclude that mainly three species contribute to the signal: a PB-PSII-PSI megacomplex with closed PSII RCs and (i) slow PB → PSI energy transfer, or (ii) fast PB → PSI energy transfer and (iii) complexes with open (photochemically quenched) PSII RCs. Furthermore, their time profiles reveal an adaptive response that we identify as a state transition. Our results suggest that deceleration of the PB → PSI energy transfer rate is the molecular mechanism underlying a state 2 to state 1 transition.
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Affiliation(s)
- Alonso M Acuña
- LaserLaB, Department of Physics and Astronomy, Faculty of Science, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands
| | - Pascal van Alphen
- Swammerdam Institute for Life Sciences, University of Amsterdam, 1098 XH, Amsterdam, The Netherlands
| | - Filipe Branco Dos Santos
- Swammerdam Institute for Life Sciences, University of Amsterdam, 1098 XH, Amsterdam, The Netherlands
| | - Rienk van Grondelle
- LaserLaB, Department of Physics and Astronomy, Faculty of Science, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands
| | - Klaas J Hellingwerf
- Swammerdam Institute for Life Sciences, University of Amsterdam, 1098 XH, Amsterdam, The Netherlands
| | - Ivo H M van Stokkum
- LaserLaB, Department of Physics and Astronomy, Faculty of Science, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands.
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7
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Maksimov EG, Mironov KS, Trofimova MS, Nechaeva NL, Todorenko DA, Klementiev KE, Tsoraev GV, Tyutyaev EV, Zorina AA, Feduraev PV, Allakhverdiev SI, Paschenko VZ, Los DA. Membrane fluidity controls redox-regulated cold stress responses in cyanobacteria. Photosynth Res 2017; 133:215-223. [PMID: 28110449 DOI: 10.1007/s11120-017-0337-333] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 11/13/2016] [Accepted: 01/08/2017] [Indexed: 05/19/2023]
Abstract
Membrane fluidity is the important regulator of cellular responses to changing ambient temperature. Bacteria perceive cold by the transmembrane histidine kinases that sense changes in thickness of the cytoplasmic membrane due to its rigidification. In the cyanobacterium Synechocystis, about a half of cold-responsive genes is controlled by the light-dependent transmembrane histidine kinase Hik33, which also partially controls the responses to osmotic, salt, and oxidative stress. This implies the existence of some universal, but yet unknown signal that triggers adaptive gene expression in response to various stressors. Here we selectively probed the components of photosynthetic machinery and functionally characterized the thermodynamics of cyanobacterial photosynthetic membranes with genetically altered fluidity. We show that the rate of oxidation of the quinone pool (PQ), which interacts with both photosynthetic and respiratory electron transport chains, depends on membrane fluidity. Inhibitor-induced stimulation of redox changes in PQ triggers cold-induced gene expression. Thus, the fluidity-dependent changes in the redox state of PQ may universally trigger cellular responses to stressors that affect membrane properties.
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Affiliation(s)
- Eugene G Maksimov
- Department of Biophysics, Faculty of Biology, M.V. Lomonosov Moscow State University, Moscow, Russia, 119992
| | - Kirill S Mironov
- Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow, Russia, 127276
| | - Marina S Trofimova
- Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow, Russia, 127276
| | - Natalya L Nechaeva
- Chemical Enzymology Department, Faculty of Chemistry, M.V. Lomonosov Moscow State University, Moscow, Russia, 119992
| | - Daria A Todorenko
- Department of Biophysics, Faculty of Biology, M.V. Lomonosov Moscow State University, Moscow, Russia, 119992
| | - Konstantin E Klementiev
- Department of Biophysics, Faculty of Biology, M.V. Lomonosov Moscow State University, Moscow, Russia, 119992
| | - Georgy V Tsoraev
- Department of Biophysics, Faculty of Biology, M.V. Lomonosov Moscow State University, Moscow, Russia, 119992
| | - Eugene V Tyutyaev
- Department of Biotechnology, Bioengineering and Biochemistry, Faculty Biotechnology and Biology, Ogarev Mordovia State University, Saransk, Republic of Mordovia, Russia, 430032
| | - Anna A Zorina
- Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow, Russia, 127276
| | - Pavel V Feduraev
- Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow, Russia, 127276
- Chemical-Biological Institute, Immanuel Kant Federal Baltic University, Kaliningrad, Russia, 236041
| | | | - Vladimir Z Paschenko
- Department of Biophysics, Faculty of Biology, M.V. Lomonosov Moscow State University, Moscow, Russia, 119992
| | - Dmitry A Los
- Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow, Russia, 127276.
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8
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Maksimov EG, Mironov KS, Trofimova MS, Nechaeva NL, Todorenko DA, Klementiev KE, Tsoraev GV, Tyutyaev EV, Zorina AA, Feduraev PV, Allakhverdiev SI, Paschenko VZ, Los DA. Membrane fluidity controls redox-regulated cold stress responses in cyanobacteria. Photosynth Res 2017; 133:215-223. [PMID: 28110449 DOI: 10.1007/s11120-017-0337-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2016] [Accepted: 01/08/2017] [Indexed: 06/06/2023]
Abstract
Membrane fluidity is the important regulator of cellular responses to changing ambient temperature. Bacteria perceive cold by the transmembrane histidine kinases that sense changes in thickness of the cytoplasmic membrane due to its rigidification. In the cyanobacterium Synechocystis, about a half of cold-responsive genes is controlled by the light-dependent transmembrane histidine kinase Hik33, which also partially controls the responses to osmotic, salt, and oxidative stress. This implies the existence of some universal, but yet unknown signal that triggers adaptive gene expression in response to various stressors. Here we selectively probed the components of photosynthetic machinery and functionally characterized the thermodynamics of cyanobacterial photosynthetic membranes with genetically altered fluidity. We show that the rate of oxidation of the quinone pool (PQ), which interacts with both photosynthetic and respiratory electron transport chains, depends on membrane fluidity. Inhibitor-induced stimulation of redox changes in PQ triggers cold-induced gene expression. Thus, the fluidity-dependent changes in the redox state of PQ may universally trigger cellular responses to stressors that affect membrane properties.
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Affiliation(s)
- Eugene G Maksimov
- Department of Biophysics, Faculty of Biology, M.V. Lomonosov Moscow State University, Moscow, Russia, 119992
| | - Kirill S Mironov
- Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow, Russia, 127276
| | - Marina S Trofimova
- Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow, Russia, 127276
| | - Natalya L Nechaeva
- Chemical Enzymology Department, Faculty of Chemistry, M.V. Lomonosov Moscow State University, Moscow, Russia, 119992
| | - Daria A Todorenko
- Department of Biophysics, Faculty of Biology, M.V. Lomonosov Moscow State University, Moscow, Russia, 119992
| | - Konstantin E Klementiev
- Department of Biophysics, Faculty of Biology, M.V. Lomonosov Moscow State University, Moscow, Russia, 119992
| | - Georgy V Tsoraev
- Department of Biophysics, Faculty of Biology, M.V. Lomonosov Moscow State University, Moscow, Russia, 119992
| | - Eugene V Tyutyaev
- Department of Biotechnology, Bioengineering and Biochemistry, Faculty Biotechnology and Biology, Ogarev Mordovia State University, Saransk, Republic of Mordovia, Russia, 430032
| | - Anna A Zorina
- Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow, Russia, 127276
| | - Pavel V Feduraev
- Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow, Russia, 127276
- Chemical-Biological Institute, Immanuel Kant Federal Baltic University, Kaliningrad, Russia, 236041
| | | | - Vladimir Z Paschenko
- Department of Biophysics, Faculty of Biology, M.V. Lomonosov Moscow State University, Moscow, Russia, 119992
| | - Dmitry A Los
- Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow, Russia, 127276.
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Abstract
Mitochondria possess oxygen-consuming respiratory electron transfer chains (RETCs), and the oxygen-evolving photosynthetic electron transfer chain (PETC) resides in chloroplasts. Evolutionarily mitochondria and chloroplasts are derived from ancient α-proteobacteria and cyanobacteria, respectively. However, cyanobacteria harbor both RETC and PETC on their thylakoid membranes. It is proposed that chloroplasts could possess a RETC on the thylakoid membrane, in addition to PETC. Identification of a plastid terminal oxidase (PTOX) in the chloroplast from the Arabidopsis variegation mutant immutans (im) demonstrated the presence of a RETC in chloroplasts, and the PTOX is the committed oxidase. PTOX is distantly related to the mitochondrial alternative oxidase (AOX), which is responsible for the CN-insensitive alternative RETC. Similar to AOX, an ubiquinol (UQH2) oxidase, PTOX is a plastoquinol (PQH2) oxidase on the chloroplast thylakoid membrane. Lack of PTOX, Arabidopsis im showed a light-dependent variegation phenotype; and mutant plants will not survive the mediocre light intensity during its early development stage. PTOX is very important for carotenoid biosynthesis, since the phytoene desaturation, a key step in the carotenoid biosynthesis, is blocked in the white sectors of Arabidopsis im mutant. PTOX is found to be a stress-related protein in numerous research instances. It is generally believed that PTOX can protect plants from various environmental stresses, especially high light stress. PTOX also plays significant roles in chloroplast development and plant morphogenesis. Global physiological roles played by PTOX could be a direct or indirect consequence of its PQH2 oxidase activity to maintain the PQ pool redox state on the thylakoid membrane. The PTOX-dependent chloroplast RETC (so-called chlororespiration) does not contribute significantly when chloroplast PETC is normally developed and functions well. However, PTOX-mediated RETC could be the major force to regulate the PQ pool redox balance in the darkness, under conditions of stress, in nonphotosynthetic plastids, especially in the early development from proplastids to chloroplasts.
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Affiliation(s)
- D Wang
- The Key Laboratory of Western Resources Biology and Biological Technology, College of Life Sciences, Northwest University, Xian, China; Shaanxi Province Key Laboratory of Biotechnology, College of Life Sciences, Northwest University, Xian, China
| | - A Fu
- The Key Laboratory of Western Resources Biology and Biological Technology, College of Life Sciences, Northwest University, Xian, China; Shaanxi Province Key Laboratory of Biotechnology, College of Life Sciences, Northwest University, Xian, China.
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Tongra T, Jajoo A. Investigating changes in the redox state of Photosystem I at low pH. J Photochem Photobiol B 2015; 151:25-30. [PMID: 26151897 DOI: 10.1016/j.jphotobiol.2015.06.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2015] [Revised: 06/30/2015] [Accepted: 06/30/2015] [Indexed: 11/29/2022]
Abstract
Changes in the redox state of Photosystem I (PSI) were studied in spinach leaf discs suspended in buffers of different pH (pH 7.5, 6.5, 5.5 and 4.5). By measuring absorbance changes at 820 nm, it was observed that under normal conditions, the electrons were supplied by Photosystem II (PSII) for the photo-oxidation of P700 while in the presence of DCMU when electrons coming from PSII are blocked, cyclic electron flow (CEF) around PSI was the major source for the absorbance changes observed at 820 nm. This was supported by complete inhibition in the reduction of both single turnover (ST) area and multiple turnover (MT) area, in the presence of DCMU, which is generally filled up by the electrons coming from PSII. In the absence of DCMU, the intersystem electron pool or plastoquinone (PQ) pool was increased at low pH which was probably due to enhanced cyclic electron flow around PSI. Our results also suggest that at low pH, in the absence of DCMU, the major contribution for faster dark re-reduction of P700(+) is attributed mainly by PSII and CEF PSI while in the presence of DCMU, the significant contribution is provided by CEF PSI and other stromal components.
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Affiliation(s)
- Teena Tongra
- School of Life Science, Devi Ahilya University, Indore 452017, M.P., India
| | - Anjana Jajoo
- School of Life Science, Devi Ahilya University, Indore 452017, M.P., India.
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