scholarly journals Providing an additional electron sink by the introduction of cyanobacterial flavodiirons enhances the growth of Arabidopsis thaliana in varying light

2020 ◽  
Author(s):  
Suresh Tula ◽  
Fahimeh Shahinnia ◽  
Michael Melzer ◽  
Twan Rutten ◽  
Rodrigo Gómez ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Electron Transport ◽  
Photosystem I ◽  
Photosynthetic Electron Transport ◽  
Photosynthetic Performance ◽  
Growth Potential ◽  
Photochemical Quenching ◽  
Transport Chain ◽  
Non Photochemical Quenching ◽  
Electron Sink

AbstractThe ability of plants to maintain photosynthesis in a dynamically changing environment is of central importance for their growth. As their photosynthetic machinery typically cannot adapt rapidly to fluctuations in the intensity of radiation, the level of photosynthetic efficiency is not always optimal. Cyanobacteria, algae, non-vascular plants (mosses and liverworts) and gymnosperms all produce flavodiirons (Flvs), a class of proteins not represented in the angiosperms; these proteins act to mitigate the photoinhibition of photosystem I. Here, genes specifying two cyanobacterial Flvs have been expressed in the chloroplasts of Arabidopsis thaliana in an attempt to improve the robustness of Photosystem I (PSI). The expression of Flv1 and Flv3 together shown to enhance the efficiency of the utilization of light and to boost the plant’s capacity to accumulate biomass. Based on an assessment of the chlorophyll fluorescence in the transgenic plants, the implication was that photosynthetic activity (including electron transport flow and non-photochemical quenching during a dark-to-light transition) was initiated earlier in the transgenic than in wild type plants. The improved photosynthetic performance of the transgenics was accompanied by an increased production of ATP, an acceleration of carbohydrate metabolism and a more pronounced partitioning of sucrose into starch. The indications are that Flvs are able to establish an efficient electron sink downstream of PSI, thereby ensuring that the photosynthetic electron transport chain remains in a more oxidized state. The expression of Flvs in a plant acts to both protect photosynthesis and to control the ATP/NADPH ratio; together, their presence is beneficial for the plant’s growth potential.

scholarly journals Flavodiiron proteins act as safety valve for electrons in Physcomitrella patens

2016 ◽  
Vol 113 (43) ◽  
pp. 12322-12327 ◽  
Author(s):  
Caterina Gerotto ◽  
Alessandro Alboresi ◽  
Andrea Meneghesso ◽  
Martina Jokel ◽  
Marjaana Suorsa ◽  
...  
Keyword(s):  
Electron Transport ◽  
Photosystem I ◽  
Physcomitrella Patens ◽  
Safety Valve ◽  
Cell Metabolism ◽  
Photosynthetic Apparatus ◽  
Photosynthetic Electron Transport ◽  
Flowering Plants ◽  
Knock Out ◽  
Electron Sink

Photosynthetic organisms support cell metabolism by harvesting sunlight to fuel the photosynthetic electron transport. The flow of excitation energy and electrons in the photosynthetic apparatus needs to be continuously modulated to respond to dynamics of environmental conditions, and Flavodiiron (FLV) proteins are seminal components of this regulatory machinery in cyanobacteria. FLVs were lost during evolution by flowering plants, but are still present in nonvascular plants such as Physcomitrella patens. We generated P. patens mutants depleted in FLV proteins, showing their function as an electron sink downstream of photosystem I for the first seconds after a change in light intensity. flv knock-out plants showed impaired growth and photosystem I photoinhibition when exposed to fluctuating light, demonstrating FLV’s biological role as a safety valve from excess electrons on illumination changes. The lack of FLVs was partially compensated for by an increased cyclic electron transport, suggesting that in flowering plants, the FLV’s role was taken by other alternative electron routes.

Rewiring photosynthesis: a photosystem I-hydrogenase chimera that makes H2in vivo

2020 ◽  
Vol 13 (9) ◽  
pp. 2903-2914 ◽  
Author(s):  
Andrey Kanygin ◽  
Yuval Milrad ◽  
Chandrasekhar Thummala ◽  
Kiera Reifschneider ◽  
Patricia Baker ◽  
...  
Keyword(s):  
Electron Transport ◽  
Hydrogen Production ◽  
Photosystem I ◽  
Electron Transport Chain ◽  
Electron Flow ◽  
Photosynthetic Electron Transport ◽  
Photosynthetic Electron Transport Chain ◽  
Transport Chain

Photosystem I-hydrogenase chimera intercepts electron flow directly from the photosynthetic electron transport chain and directs it to hydrogen production.

scholarly journals The chloroplast NADPH thioredoxin reductase C, NTRC, controls non-photochemical quenching of light energy and photosynthetic electron transport inArabidopsis

2016 ◽  
Vol 39 (4) ◽  
pp. 804-822 ◽  
Author(s):  
Belén Naranjo ◽  
Clara Mignée ◽  
Anja Krieger-Liszkay ◽  
Dámaso Hornero-Méndez ◽  
Lourdes Gallardo-Guerrero ◽  
...  
Keyword(s):  
Electron Transport ◽  
Thioredoxin Reductase ◽  
Photosynthetic Electron Transport ◽  
Light Energy ◽  
Photochemical Quenching ◽  
Non Photochemical Quenching

scholarly journals Expression of Glutamate Dehydrogenase Genes In Arabidopsis Thaliana Depends on The Redox State of Chloroplast Electron Transport Chain

2021 ◽  
Author(s):  
Elena Yu. Garnik ◽  
Vadim I. Belkov ◽  
Vladislav I. Tarasenko ◽  
Yury M. Konstantinov
Keyword(s):  
Arabidopsis Thaliana ◽  
Electron Transport ◽  
Glutamate Dehydrogenase ◽  
Electron Transport Chain ◽  
Redox State ◽  
Photosynthetic Electron Transport ◽  
Glucose Content ◽  
Tetrapyrrole Synthesis ◽  
Transport Chain ◽  
Significant Difference

Abstract Plant glutamate dehydrogenase is an enzyme interconverting L-glutamate and 2-oxoglutarate and providing a link between carbon and nitrogen metabolism. In Arabidopsis thaliana, this enzyme is encoded by three genes. Two of them, GDH1 and GDH2, provide most of the enzyme activity in plant leaves and roots. Expression of GDH1 and GDH2 genes is very low in the light and high in the dark. The molecular signals and mechanisms that provide the light-dependent GDH genes regulation remain unknown. Using photosynthetic electron transport inhibitors 3-(3.4-dichlorophenyl)-1.1-dimethylurea (DCMU) and 2.5-dibromo-3-methyl-6-isopropyl benzoquinone (DBMIB) we demonstrate that transcript levels of the GDH1 and GDH2 genes in Arabidopsis leaves change in accordance with a redox state of chloroplast electron transport chain: they are low when it is highly reduced and high when it is oxidized. Hydrogen peroxide or high light treatment did not result in decreasing of GDH1 or GDH2 expression, so reactive oxygen species cannot be the signals that reduce expression of these genes during dark-to-light shifts. There was no significant difference between the glucose content in the leaves of plants treated with DCMU and the plants treated with DBMIB, so glucose is not the only or the main factor that regulates expression of the studied genes. We presume that expression of Arabidopsis GDH1 and GDH2 genes depends on the chloroplast electron transport chain redox state. This regulatory mechanism could arise because of a need to avoid a competition for substrate between tetrapyrrole synthesis, glutathione synthesis and using of L-glutamate as an energy source during prolonged darkness.

Stoichiometric Photophosphorylation in Thylakoids from the Blue-Green Alga, Anabaena variabilis

1980 ◽  
Vol 35 (1-2) ◽  
pp. 98-105 ◽  
Author(s):  
Erika Wax ◽  
Wolfgang Lockau
Keyword(s):  
Electron Transport ◽  
Green Alga ◽  
Photosystem I ◽  
Electron Transport Chain ◽  
Photosynthetic Electron Transport ◽  
Anabaena Variabilis ◽  
Blue Green Alga ◽  
Photosynthetic Electron Transport Chain ◽  
Transport Chain ◽  
Photosynthetic Control

Abstract A method is described for the preparation of thylakoids from the blue-green alga Anabaena variabilis which exhibit photosynthetic control. The thylakoids can be stored in liquid N 2 with little loss in activity. P/e2 ratios (num ber of ATP molecules formed per pair of electrons transported) have been determined for partial reactions of the photosynthetic electron transport chain. Electron transport from water to an electron acceptor of photosystem I is coupled to phosphorylation with a P/e2 ratio of 0.9-1.2, from water to electron acceptors of photosystem II with ratios of 0.21-0.3 , and oxidations of hydrogen carriers by photosystem I with ratios of 0.3-0.35. Electron transport in these assay systems generates a proton gradient across the thylakoid membrane (acid inside), which is decreased by the substrates of phosphorylation and by uncouplers.

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.

scholarly journals Improved photosynthetic capacity and photosystem I oxidation via heterologous metabolism engineering in cyanobacteria

2021 ◽  
Vol 118 (11) ◽  
pp. e2021523118
Author(s):  
María Santos-Merino ◽  
Alejandro Torrado ◽  
Geoffry A. Davis ◽  
Annika Röttig ◽  
Thomas S. Bibby ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Electron Transport ◽  
Photosystem I ◽  
Metabolic Pathways ◽  
Electron Transport Chain ◽  
Photosynthetic Apparatus ◽  
Photosynthetic Performance ◽  
Cytochrome P450 Activity ◽  
Transport Chain ◽  
Source Sink

Cyanobacteria must prevent imbalances between absorbed light energy (source) and the metabolic capacity (sink) to utilize it to protect their photosynthetic apparatus against damage. A number of photoprotective mechanisms assist in dissipating excess absorbed energy, including respiratory terminal oxidases and flavodiiron proteins, but inherently reduce photosynthetic efficiency. Recently, it has been hypothesized that some engineered metabolic pathways may improve photosynthetic performance by correcting source/sink imbalances. In the context of this subject, we explored the interconnectivity between endogenous electron valves, and the activation of one or more heterologous metabolic sinks. We coexpressed two heterologous metabolic pathways that have been previously shown to positively impact photosynthetic activity in cyanobacteria, a sucrose production pathway (consuming ATP and reductant) and a reductant-only consuming cytochrome P450. Sucrose export was associated with improved quantum yield of phtotosystem II (PSII) and enhanced electron transport chain flux, especially at lower illumination levels, while cytochrome P450 activity led to photosynthetic enhancements primarily observed under high light. Moreover, coexpression of these two heterologous sinks showed additive impacts on photosynthesis, indicating that neither sink alone was capable of utilizing the full “overcapacity” of the electron transport chain. We find that heterologous sinks may partially compensate for the loss of photosystem I (PSI) oxidizing mechanisms even under rapid illumination changes, although this compensation is incomplete. Our results provide support for the theory that heterologous metabolism can act as a photosynthetic sink and exhibit some overlapping functionality with photoprotective mechanisms, while potentially conserving energy within useful metabolic products that might otherwise be “lost.”

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