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

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.

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Exposure of high-light-grown cultures of Chlorella vulgaris to darkness inhibits the relaxation of excitation pressure: uncoupling of the redox state of the photosynthetic electron transport chain and phenotypic plasticity

Botany ◽

10.1139/cjb-2017-0066 ◽

2017 ◽

Vol 95 (12) ◽

pp. 1125-1140 ◽

Cited By ~ 1

Author(s):

Lauren Hollis ◽

Norman P.A. Hüner

Keyword(s):

Electron Transport ◽

Chlorella Vulgaris ◽

Electron Transport Chain ◽

Redox State ◽

Light Harvesting ◽

Photosynthetic Electron Transport ◽

High Light ◽

Photon Flux ◽

Photosynthetic Electron Transport Chain ◽

Transport Chain

Chlorella vulgaris acclimated to high light (HL) conditions exhibited a pale-green phenotype characterized by reduced chlorophyll and light harvesting polypeptide abundance compared with the dark green phenotype of the control, low-light-grown (LL) cultures. We hypothesized that if chloroplast redox status was the sole regulator of phenotype, exposure to darkness should cause reversion of the HL to LL phenotype. Surprisingly, HL cells transferred to darkness or dim light failed to green. Thus, phenotypic reversion is light-dependent with an optimal photon flux density (PFD) of 110 μmol photons·m−2·s−1. HL cells shifted to this PFD exhibited increased chlorophyll and light harvesting polypeptide abundance, which were inhibited by 2,5-dibromo-3-methyl-6-isopropyl-benzoquinone but not by 3-(3′,4′-dichlorophenyl)-1,1-dimethylurea. We conclude that photoacclimation of HL-grown cells to LL is governed by the redox state of the intersystem photosynthetic electron transport chain (PETC) at this PFD. At lower light levels, cells maintained the HL phenotype, despite an oxidized status of the PETC. Because 110 μmol photons·m−2·s−1 was the optimal PFD for protochlorophyllide oxidoreductase accumulation, we suggest that stabilization of light-harvesting polypeptides by chlorophyll binding may also govern photoacclimation in C. vulgaris. The possible role of the metabolic balance between respiration and photosynthesis is also discussed.

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

Plants ◽

10.3390/plants9091157 ◽

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.

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In vitro analysis of the plastid terminal oxidase in photosynthetic electron transport

Biochimica et Biophysica Acta (BBA) - Bioenergetics ◽

10.1016/j.bbabio.2014.07.016 ◽

2014 ◽

Vol 1837 (10) ◽

pp. 1684-1690 ◽

Cited By ~ 9

Author(s):

Kathleen Feilke ◽

Qiuju Yu ◽

Peter Beyer ◽

Pierre Sétif ◽

Anja Krieger-Liszkay

Keyword(s):

Electron Transport ◽

Photosynthetic Electron Transport ◽

Terminal Oxidase ◽

Vitro Analysis ◽

Plastid Terminal Oxidase ◽

In Vitro Analysis

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The Photosynthetic Electron Transport Chain of Chlamydomonas reinhardi

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)51827-5 ◽

1963 ◽

Vol 238 (12) ◽

pp. 4052-4057

Author(s):

R.P. Levine ◽

R.M. Smillie

Keyword(s):

Electron Transport ◽

Electron Transport Chain ◽

Photosynthetic Electron Transport ◽

Photosynthetic Electron Transport Chain ◽

Transport Chain

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The Photosynthetic Electron Transport Chain of Chlamydomonas reinhardi

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)51828-7 ◽

1963 ◽

Vol 238 (12) ◽

pp. 4058-4062 ◽

Cited By ~ 1

Author(s):

R.M. Smillie ◽

R.P. Levine

Keyword(s):

Electron Transport ◽

Electron Transport Chain ◽

Photosynthetic Electron Transport ◽

Photosynthetic Electron Transport Chain ◽

Transport Chain

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

International Journal of Molecular Sciences ◽

10.3390/ijms22084021 ◽

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.

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

Zeitschrift für Naturforschung C ◽

10.1515/znc-1986-5-618 ◽

1986 ◽

Vol 41 (5-6) ◽

pp. 597-603 ◽

Cited By ~ 33

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.

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Effects of Different Planting Densities on Photosynthesis in Maize Determined via Prompt Fluorescence, Delayed Fluorescence and P700 Signals

Plants ◽

10.3390/plants10020276 ◽

2021 ◽

Vol 10 (2) ◽

pp. 276

Author(s):

Wanying Chen ◽

Bo Jia ◽

Junyu Chen ◽

Yujiao Feng ◽

Yue Li ◽

...

Keyword(s):

Electron Transport ◽

Chlorophyll A ◽

Chlorophyll A Fluorescence ◽

Electron Transport Chain ◽

Plant Density ◽

Photosynthetic Electron Transport ◽

Planting Density ◽

Strong Impact ◽

Photosynthetic Electron Transport Chain ◽

Transport Chain

The mutual shading among individual field-grown maize plants resulting from high planting density inevitably reduces leaf photosynthesis, while regulating the photosynthetic transport chain has a strong impact on photosynthesis. However, the effect of high planting density on the photosynthetic electron transport chain in maize currently remains unclear. In this study, we simultaneously measured prompt chlorophyll a fluorescence (PF), modulated 820 nm reflection (MR) and delayed chlorophyll a fluorescence (DF) in order to investigate the effect of high planting density on the photosynthetic electron transport chain in two maize hybrids widely grown in China. PF transients demonstrated a gradual reduction in their signal amplitude with increasing planting density. In addition, high planting density induced positive J-step and G-bands of the PF transients, reduced the values of PF parameters PIABS, RC/CSO, TRO/ABS, ETO/TRO and REO/ETO, and enhanced ABS/RC and N. MR kinetics showed an increase of their lowest point with increasing high planting density, and thus the values of MR parameters VPSI and VPSII-PSI were reduced. The shapes of DF induction and decay curves were changed by high planting density. In addition, high planting density reduced the values of DF parameters I1, I2, L1 and L2, and enhanced I2/I1. These results suggested that high planting density caused harm on multiple components of maize photosynthetic electron transport chain, including an inactivation of PSII RCs, a blocked electron transfer between QA and QB, a reduction in PSI oxidation and re-reduction activities, and an impaired PSI acceptor side. Moreover, a comparison between PSII and PSI activities demonstrated the greater effect of plant density on the former.

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