scholarly journals The Role of Selected Wavelengths of Light in the Activity of Photosystem II in Gloeobacter violaceus

2021 ◽  
Vol 22 (8) ◽  
pp. 4021
Author(s):  
Monika Kula-Maximenko ◽  
Kamil Jan Zieliński ◽  
Ireneusz Ślesak
Keyword(s):  
Photosystem Ii ◽  
Spectral Composition ◽  
Photosynthetic Electron Transport ◽  
Metabolic Energy ◽  
Light Conditions ◽  
Gloeobacter Violaceus ◽  
Transport Chain ◽  
Cyanobacterial Culture ◽  
Photosynthetic Antennas

Gloeobacter violaceus is a cyanobacteria species with a lack of thylakoids, while photosynthetic antennas, i.e., phycobilisomes (PBSs), photosystem II (PSII), and I (PSI), are located in the cytoplasmic membrane. We verified the hypothesis that blue–red (BR) light supplemented with a far-red (FR), ultraviolet A (UVA), and green (G) light can affect the photosynthetic electron transport chain in PSII and explain the differences in the growth of the G. violaceus culture. The cyanobacteria were cultured under different light conditions. The largest increase in G. violaceus biomass was observed only under BR + FR and BR + G light. Moreover, the shape of the G. violaceus cells was modified by the spectrum with the addition of G light. Furthermore, it was found that both the spectral composition of light and age of the cyanobacterial culture affect the different content of phycobiliproteins in the photosynthetic antennas (PBS). Most likely, in cells grown under light conditions with the addition of FR and G light, the average antenna size increased due to the inactivation of some reaction centers in PSII. Moreover, the role of PSI and gloeorhodopsin as supplementary sources of metabolic energy in the G. violaceus growth is discussed.

The atypical kinase ABC1K1 interacts with the EXECUTER pathway to promote chloroplast biogenesis.

2021 ◽  
Author(s):  
Joy Collombat ◽  
Thibaut Pralon ◽  
Jenny Pego Magalhaes ◽  
Sarah Rottet ◽  
Brigitte Ksas ◽  
...  
Keyword(s):  
Electron Transport Chain ◽  
Red Light ◽  
Photosynthetic Electron Transport ◽  
Chloroplast Biogenesis ◽  
Light Conditions ◽  
Photosynthetic Electron Transport Chain ◽  
Transport Chain ◽  
Dependent Signal ◽  
Photosynthetic Mutants

Abstract Multiple chloroplast-to-nucleus signaling pathways contribute to the regulation of chloroplast biogenesis during plant greening. Here, we provide evidence for the direct implication of the atypical kinase ABC1K1. ABC1K1 is required for sufficient plastoquinone (PQ) allocation to the photosynthetic electron transport chain. Unexpectedly, mutation of abc1k1 suppresses greening and results in pale cotyledons under red light. This phenotype was not observed in other photosynthetic mutants and points to a specific signaling defect. Under red light, abc1k1 accumulated EXECUTER1 (EX1), a trigger of singlet oxygen (1O2) signaling. Consistent with the role of the FTSH metalloprotease in chloroplast biogenesis and EX1 degradation, the ftsh2 mutant var2, mimicked the greening defect of abc1k1 and accumulated EX1 under red light. We propose that this novel ABC1K1-dependent signal is required for chloroplast biogenesis to progress in challenging light conditions.

Changes in the Stoichiometry of Photosystem II Components as an Adaptive Response to High-Light and Low-Light Conditions during Growth

1986 ◽  
Vol 41 (5-6) ◽  
pp. 597-603 ◽  
Author(s):  
Aloysius Wild ◽  
Matthias Höpfner ◽  
Wolfgang Rühle ◽  
Michael Richter
Keyword(s):  
Photosystem Ii ◽  
Functional Organization ◽  
Photosynthetic Apparatus ◽  
High Light ◽  
Molar Ratio ◽  
Light Conditions ◽  
Low Light ◽  
Pigment System ◽  
Transport Chain ◽  
The One

The effect of different growth light intensities (60 W·m-2, 6 W·m-2) on the performance of the photosynthetic apparatus of mustard plants (Sinapis alba L.) was studied. A distinct decrease in photosystem II content per chlorophyll under low-light conditions compared to high-light conditions was found. For P-680 as well as for Oᴀ and Oв protein the molar ratio between high-light and low-light plants was 1.4 whereas the respective concentrations per chlorophyll showed some variations for P-680 and Oᴀ on the one and Oв protein on the other hand.In addition to the study of photosystem II components, the concentrations of PQ, Cyt f, and P-700 were measured. The light regime during growth had no effect on the amount of P-700 per chlorophyll but there were large differences with respect to PQ and Cyt f. The molar ratio for Cyt f and PQ between high- and low-light leaves was 2.2 and 1.9, respectively.Two models are proposed, showing the functional organization of the pigment system and the electron transport chain in thylakoids of high-light and low-light leaves of mustard plants.

Photosynthetic components and activities of nitrogen-fixing isolated heterocysts of Anabaena cylindrica

1977 ◽  
Vol 198 (1130) ◽  
pp. 61-86 ◽  
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Cytochrome B ◽  
Nitrogenase Activity ◽  
Photosynthetic Electron Transport ◽  
Central Component ◽  
Reaction Centre ◽  
Anabaena Cylindrica ◽  
Higher Plant ◽  
Transport Chain

Isolated heterocysts of the N 2 -fixing Anabaena cylindrica , prepared by a combination of lysozyme and Yeda press treatments, are metabolically active with over 90% of the measurable nitrogenase activity being located in the heterocyst preparations after disruption of the intact filaments. The photosynthetic activities of such isolated heterocysts are characterized by an inability to carry out the photolysis of water or to fix CO 2 . The lack of O 2 evolution appears to be due in part to the deple­tion during heterocyst differentiation of Mn, a central component of the photosystem II reaction centre in O 2 -evolving algae. There is evidence that components of the photosynthetic electron transport chain on the reducing side of the photosystem II reaction centre are present and functional in heterocysts. These include cytochrome c 554 , plastocyanin, plastoquinone, cytochrome b 559 , P700, cytochrome b 563 , and iron-sulphur proteins which appear to correspond to centre A and centre B of higher plant chloroplasts. Soluble, or loosely bound ferredoxin is also present and involved in electron transport from ferredoxin to NADP. Isolated heterocysts photoreduce methylviologen when reduced 2,6-dichlorophenolindophenol and diphenylcarbazide serve as electron donors. They show P700 photo-oxidation and photoreduction, photosyn­thetic electron transport which is inhibited by 2,5-dibromo-3-methyl-6-isopropyl- p -benzoquinone an antagonist of plastoquinone, photophos­phorylation, oxidative phosphorylation and ferredoxin-NADP oxido-reductase mediated reactions. The photosynthetic modifications of the heterocyst are such that electron transport and the generation of ATP for nitrogenase can occur without concomitant O 2 evolution and with­out nitrogenase having to compete with CO 2 fixation for ATP and reductant.

The PedR transcriptional regulator interacts with thioredoxin to connect photosynthesis with gene expression in cyanobacteria

2010 ◽  
Vol 431 (1) ◽  
pp. 135-140 ◽  
Author(s):  
Mayumi Horiuchi ◽  
Kinu Nakamura ◽  
Kouji Kojima ◽  
Yoshitaka Nishiyama ◽  
Wakako Hatakeyama ◽  
...  
Keyword(s):  
Electron Transport ◽  
Conformational Change ◽  
Photosynthetic Electron Transport ◽  
Transcript Level ◽  
High Light ◽  
Light Conditions ◽  
Transport Chain ◽  
Acclimation Response ◽  
Vitro Analysis

The redox state of the photosynthetic electron transport chain acts as a critical sensing mechanism by regulating the transcription of key genes involved in the acclimation response to a change in the environment. In the present study we show that the small LuxR-type regulator PedR interacts with Trx (thioredoxin) to achieve photosynthetic electron-transport-dependent transcriptional regulation in the cyanobacterium Synechocystis sp. PCC 6803. TrxM, an isoform of Trx, was isolated as an interacting factor of PedR by pull-down assays. In vitro analysis revealed that the intermolecular disulfide bond formed between Cys80 residues of the PedR homodimer was reduced by both TrxM and TrxX. It has been shown previously that, although PedR is active under low-light conditions, it becomes transiently inactivated following a shift to high-light conditions, with a concomitant conformational change [Nakamura and Hihara (2006) J. Biol. Chem. 281, 36758–36766]. In the present study, we found that the conformational change of PedR and the change in the transcript level of its target gene were minimal when mutants of Synechocystis that lack ferredoxin–Trx reductase or NADPH–Trx reductase were exposed to high levels of light. These results indicate that the reduction of PedR by Trx causes transient inactivation of PedR upon the shift of cyanobacterial cells to high-light conditions.

The Role of D 1* in Light-Induced D 1 Protein Turnover in Leaves

1993 ◽  
Vol 48 (3-4) ◽  
pp. 246-250
Author(s):  
Anna J. Syme ◽  
Harald R . Bolhàr-N ordenkampf ◽  
Christa Critchley
Keyword(s):  
Chlorophyll Fluorescence ◽  
Photosystem Ii ◽  
Light Intensity ◽  
Protein Turnover ◽  
Photochemical Efficiency ◽  
Light Conditions ◽  
Ps Ii ◽  
Light Intensities ◽  
Intact Leaves

Abstract Light-induced degradation of the D 1 protein of photosystem II (PS II) was determined by radioactive pulse-chase labelling experiments in intact leaves of Schefflera polybotrya. PS II photochemical efficiency was monitored by measuring chlorophyll fluorescence. A significant and consistent decline in the Fv/ Fm ratio was taken to indicate photoinhibition. The formation and degradation of a modified form of the D 1 protein, D 1*, was different under photoinhibi-tory or non-photoinhibitory light conditions. At photoinhibitory irradiance greater amounts of D 1 * were formed relative to D 1, and the degradation of D 1* was slower when compared with non-photoinhibitory irradiance. The formation and degradation of D 1* were therefore shown to be at least partly light intensity dependent. Higher light intensities appeared to slow D 1* degradation, which suggests a modification in PS II turnover properties.

scholarly journals Characterizing membrane anchoring of leaf-form ferredoxin-NADP+ oxidoreductase in rice

2021 ◽  
Author(s):  
xiaowen da ◽  
jiangfan guo ◽  
peng yan ◽  
Chao Yang ◽  
Hongfei Zhao ◽  
...  
Keyword(s):  
Thylakoid Membrane ◽  
Photosynthetic Electron Transport ◽  
Light Conditions ◽  
Membrane Anchor ◽  
Chloroplast Membranes ◽  
Leaf Form ◽  
Photosynthetic Electron Transport Chain ◽  
Transport Chain ◽  
Chloroplast Stroma ◽  
Membrane Anchoring

Leaf-form ferredoxin-NADP+ oxidoreductases (LFNRs) function in the last step of the photosynthetic electron transport chain, exist as soluble proteins in the chloroplast stroma, and are weakly associated with thylakoids or tightly anchored to chloroplast membranes. Arabidopsis thaliana has two LFNRs, and the chloroplast proteins AtTROL (THYLAKOID RHODANESE-LIKE PROTEIN) and AtTIC62 (62-kDa SUBUNIT OF TRANSLOCON OF INNER CHLOROPLAST MEMBRANE) participate in anchoring AtLFNRs to the thylakoid membrane. By contrast, the membrane anchoring mechanism of rice (Oryza sativa) LFNRs has not been elucidated. Here, we investigated the membrane-anchoring mechanism of LFNRs and its physiological roles in rice. We characterized the rice protein OsTROL1 based on its homology to AtTROL and showed that OsTROL1 is also a thylakoid membrane anchor and its loss led to a compensatory increase in OsTIC62. Moreover, OsLFNR1 attachment through a membrane anchor depends on OsLFNR2, unlike their Arabidopsis counterparts. In addition, OsTIC62 was more highly expressed in rice under dark than under light conditions, consistent with the increased membrane binding of OsLFNR in the dark. Moreover, we observed reciprocal stabilization between OsLFNRs and their membrane anchors. Therefore, our study sheds light on the mechanisms anchoring LFNRs to membranes in rice and highlights differences with Arabidopsis

Substituted p-Benzoquinones Having High Electron Affinity as Photosystem II Electron Acceptors

1980 ◽  
Vol 35 (1-2) ◽  
pp. 136-138 ◽  
Author(s):  
H. Daniell ◽  
G. Kulandaivelu ◽  
U. Chandra Singh
Keyword(s):  
Photosystem Ii ◽  
Electron Affinity ◽  
Photosynthetic Electron Transport ◽  
Electron Acceptors ◽  
High Electron ◽  
Whole Cells ◽  
High Electron Affinity ◽  
Transport Chain ◽  
Alkoxy Groups ◽  
Fold Stimulation

Abstract Substituted Benzoquinones, Photosystem II Acceptors Benzoquinones (BQ) substituted with alkyl or alkoxy groups 2,5-dimethoxy-3,6-dichloro-p-benzoquinone (DCDMQ), 2,3,5,6-tetramethoxy-p-benzoquinone (TMQ) have been tested for their electron affinity and site of action in the photosynthetic electron transport chain in whole cells and chloroplasts. Both the substituted compounds were found to be good electron acceptors of photosystem II. DCDMQ showed higher electron affinity than BQ as demonstrated by its two fold stimulation of O2 evolution in chloroplasts and efficiency in quenching DCMU fluorescence. TMQ on the other hand showed low electron affinity.

scholarly journals Aerobic Barley Mg-protoporphyrin IX Monomethyl Ester Cyclase is Powered by Electrons from Ferredoxin

Plants ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1157
Author(s):  
David Stuart ◽  
Malin Sandström ◽  
Helmy M. Youssef ◽  
Shakhira Zakhrabekova ◽  
Poul Erik Jensen ◽  
...  
Keyword(s):  
Protoporphyrin Ix ◽  
Photosynthetic Electron Transport ◽  
In Vitro Assays ◽  
Light Conditions ◽  
Hordeum Vulgare L ◽  
Transport Chain ◽  
Additional Protein ◽  
Membrane Bound ◽  
Monomethyl Ester

Chlorophyll is the light-harvesting molecule central to the process of photosynthesis. Chlorophyll is synthesized through 15 enzymatic steps. Most of the reactions have been characterized using recombinant proteins. One exception is the formation of the isocyclic E-ring characteristic of chlorophylls. This reaction is catalyzed by the Mg-protoporphyrin IX monomethyl ester cyclase encoded by Xantha-l in barley (Hordeum vulgare L.). The Xantha-l gene product (XanL) is a membrane-bound diiron monooxygenase, which requires additional soluble and membrane-bound components for its activity. XanL has so far been impossible to produce as an active recombinant protein for in vitro assays, which is required for deeper biochemical and structural analyses. In the present work, we performed cyclase assays with soluble and membrane-bound fractions of barley etioplasts. Addition of antibodies raised against ferredoxin or ferredoxin-NADPH oxidoreductase (FNR) inhibited assays, strongly suggesting that reducing electrons for the cyclase reaction involves ferredoxin and FNR. We further developed a completely recombinant cyclase assay. Expression of active XanL required co-expression with an additional protein, Ycf54. In vitro cyclase activity was obtained with recombinant XanL in combination with ferredoxin and FNR. Our experiment demonstrates that the cyclase is a ferredoxin-dependent enzyme. Ferredoxin is part of the photosynthetic electron-transport chain, which suggests that the cyclase reaction might be connected to photosynthesis under light conditions.

On the Role of Plastoquinone in Photosynthesis

1971 ◽  
Vol 26 (4) ◽  
pp. 341-352 ◽  
Author(s):  
H. Böhme ◽  
S. Reimer ◽  
A. Trebst
Keyword(s):  
Photosystem Ii ◽  
Electron Transport Chain ◽  
Electron Flow ◽  
Cyclic Electron Flow ◽  
Cyclic System ◽  
Transport Chain ◽  
Cyclic Photophosphorylation ◽  
Intact Chloroplasts ◽  
Flow Through

Dibromothymoquinone and its hydroquinone are inhibitors of non cyclic electron flow from water to NADP, anthraquinone or methylviologen. The inhibition is competetively reversed by plastoquinone. It appears that dibromothymoquinone is an antagonist of plastoquinone and that it prevents the enzymic (by the next endogenous carrier of the chloroplast electron transport chain) but not the chemical (by ferricyanide) reoxidation of reduced plastoquinone. This follows from the result that the photoreduction of ferricyanide and DCPIP * is not inhibited by dibromothymoquinone in sonicated chloroplasts and is inhibited in intact chloroplasts to only 60% or 80% respectively. It is concluded that dibromothymoquinone does not inhibit photoreductions by photosystem II.According to their response to dibromothymoquinone, cyclic photophosphorylations can be subdivided in those requiring plastoquinone and those which do not. Menadione catalyzed cyclic photophosphorylation is inhibited by dibromothymoquinone, whereas the PMS catalyzed system is not. The DAD cyclic system is only partly inhibited by dibromothymoquinone. The PMS catalyzed cyclic photophosphorylation in the presence of dibromothymoquinone is antimycin sensitive, which suggests that the PMS system can switch from a plastoquinone dependent system to a plastoquinone independent, but cytochrome b dependent system, which is now antimycin sensitive. Ferredoxin catalyzed cyclic photophosphorylation is inhibited by dibromothymoquinone as well as by antimycin. The data indicate that non cyclic electron flow through both photosystems is obligatory dependent on plastoquinone, whereas cyclic systems do not necessarily include plastoquinone. The relevance of the results to the possibility of different coupling sites in cyclic and non cyclic electron flow systems is discussed.

scholarly journals Polymer-Modified Single-Walled Carbon Nanotubes Affect Photosystem II Photochemistry, Intersystem Electron Transport Carriers and Photosystem I End Acceptors in Pea Plants

Molecules ◽  
2021 ◽  
Vol 26 (19) ◽  
pp. 5958
Author(s):  
Nia Petrova ◽  
Momchil Paunov ◽  
Petar Petrov ◽  
Violeta Velikova ◽  
Vasilij Goltsev ◽  
...  
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Photosystem I ◽  
Electron Transport Chain ◽  
Photosynthetic Electron Transport ◽  
Single Walled Carbon Nanotubes ◽  
Donor Side ◽  
Photosynthetic Electron Transport Chain ◽  
Transport Chain ◽  
Walled Carbon Nanotubes

Single-walled carbon nanotubes (SWCNT) have recently been attracting the attention of plant biologists as a prospective tool for modulation of photosynthesis in higher plants. However, the exact mode of action of SWCNT on the photosynthetic electron transport chain remains unknown. In this work, we examined the effect of foliar application of polymer-grafted SWCNT on the donor side of photosystem II, the intersystem electron transfer chain and the acceptor side of photosystem I. Analysis of the induction curves of chlorophyll fluorescence via JIP test and construction of differential curves revealed that SWCNT concentrations up to 100 mg/L did not affect the photosynthetic electron transport chain. SWCNT concentration of 300 mg/L had no effect on the photosystem II donor side but provoked inactivation of photosystem II reaction centres and slowed down the reduction of the plastoquinone pool and the photosystem I end acceptors. Changes in the modulated reflection at 820 nm, too, indicated slower re-reduction of photosystem I reaction centres in SWCNT-treated leaves. We conclude that SWCNT are likely to be able to divert electrons from the photosynthetic electron transport chain at the level of photosystem I end acceptors and plastoquinone pool in vivo. Further research is needed to unequivocally prove if the observed effects are due to specific interaction between SWCNT and the photosynthetic apparatus.

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