Functionally distinct NAD(P)H dehydrogenases and their membrane localization in Synechocystis sp. PCC6803

2002 ◽  
Vol 29 (3) ◽  
pp. 195 ◽  
Author(s):  
Hiroshi Ohkawa ◽  
Masatoshi Sonoda ◽  
Natsu Hagino ◽  
Mari Shibata ◽  
Himadri B. Pakrasi ◽  
...  
Keyword(s):  
Electron Flow ◽  
Photosynthetic Electron Transport ◽  
Transport Processes ◽  
Membrane Localization ◽  
Co2 Uptake ◽  
Type I ◽  
Synechocystis 6803 ◽  
Integrative View ◽  
Inorganic Carbon Transport ◽  
Synechocystis Sp

The type I NAD(P)H dehydrogenase complex (NDH-1) in cyanobacteria is involved in both respiratory and photosynthetic electron transport processes. NDH-1 is also essential for inorganic carbon transport. It has been postulated that NDH-1-dependent cyclic electron flow around PSI energizes CO2 uptake. The genome information of Synechocystis sp. PCC6803 has enabled us to provide an integrative view of the CO2 concentrating mechanism in this organism. In an attempt to dissect the role of the NDH-1 complex, we have constructed single and double mutants of Synechocystis 6803 by disrupting highly homologous ndhD genes in pairs, and have analysed the growth, CO2 uptake activities, and redox levels of P700 and the plastoquinone pool in these mutants under various conditions. We have also determined the membrane localization of this membrane protein. Our studies have revealed that: (i) mutations in ndh genes lead to inhibition of CO2 uptake, rather than HCO3– uptake; (ii) NDH-1 complexes are localized only in the thylakoid membrane; (iii) there are functionally distinct NDH-1 complexes in Synechocystis #6803. Based on these data, we propose a schematic view of the roles of different NDH-1 complexes in cyanobacteria.

scholarly journals Regulation of electron transport is essential for photosystem I stability and plant growth

2019 ◽  
Author(s):  
Mattia Storti ◽  
Anna Segalla ◽  
Marco Mellon ◽  
Alessandro Alboresi ◽  
Tomas Morosinotto
Keyword(s):  
Electron Transport ◽  
Photosystem I ◽  
Nadh Dehydrogenase ◽  
Physcomitrella Patens ◽  
Electron Flow ◽  
Photosynthetic Electron Transport ◽  
Type I ◽  
Growth Reduction ◽  
Light Regimes ◽  
Photosynthetic Organisms

AbstractLife depends on the ability of photosynthetic organisms to exploit sunlight to fix carbon dioxide into biomass. Photosynthesis is modulated by pathways such as cyclic and pseudocyclic electron flow (CEF and PCEF). CEF transfers electrons from photosystem I to the plastoquinone pool according to two mechanisms, one dependent on proton gradient regulators (PGR5/PGRL1) and the other on the type I NADH dehydrogenase (NDH) complex. PCEF uses electrons from photosystem I to reduce oxygen; in several groups of photosynthetic organisms but not in angiosperms, it is sustained by flavodiiron proteins (FLVs). PGR5/PGRL1, NDH and FLVs are all active in the moss Physcomitrella patens, and mutants depleted in these proteins show phenotypes under specific light regimes. Here, we demonstrated that CEF and PCEF exhibit strong functional overlap and that when one protein component is depleted, the others can compensate for most of the missing activity. When multiple mechanisms are simultaneously inactivated, however, plants show damage to photosystem I and strong growth reduction, demonstrating that mechanisms for the modulation of photosynthetic electron transport are indispensable.

scholarly journals Mutation of ndh Genes Leads to Inhibition of CO2 Uptake Rather than HCO3−Uptake in Synechocystis sp. Strain PCC 6803

2000 ◽  
Vol 182 (9) ◽  
pp. 2591-2596 ◽  
Author(s):  
Hiroshi Ohkawa ◽  
G. Dean Price ◽  
Murray R. Badger ◽  
Teruo Ogawa
Keyword(s):  
Solid Medium ◽  
Co2 Uptake ◽  
Type I ◽  
Wild Type ◽  
Uptake Capacity ◽  
Ndh Genes ◽  
Synechocystis Sp ◽  
Pcc 6803

ABSTRACT Six mutants (B1 to B6) that grew poorly in air on BG11 agar plates buffered at pH 8.0 were rescued after mutations were introduced intondhB of wild-type (WT) Synechocystis sp. strain PCC 6803. In these mutants and a mutant (M55) lacking ndhB, CO2 uptake was much more strongly inhibited than HCO3 − uptake, i.e., the activities of CO2 and HCO3 − uptake in B1 were 9 and 85% of those in the WT, respectively. Most of the mutants grew very slowly or did not grow at all at pH 6.5 or 7.0 in air, and their ability to grow under these conditions was correlated with CO2 uptake capacity. Detailed studies of B1 and M55 indicated that the mutants grew as fast as the WT in liquid at pH 8.0 under air, although they grew poorly on agar plates. The contribution of CO2 uptake appears to be larger on solid medium. Five mutants were constructed by inactivating each of the fivendhD genes in Synechocystis sp. strain PCC 6803. The mutant lacking ndhD3 grew much more slowly than the WT at pH 6.5 under 50 ppm CO2, although otherndhD mutants grew like the WT under these conditions and showed low affinity for CO2 uptake. These results indicated the presence of multiple NAD(P)H dehydrogenase type I complexes with specific roles.

Interaction of Photosystem II Herbicides with Bicarbonate and Formate in Their Effects on Photosynthetic Electron Flow

1984 ◽  
Vol 39 (5) ◽  
pp. 374-377 ◽  
Author(s):  
J. J. S. van Rensen
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Electron Flow ◽  
Photosynthetic Electron Transport ◽  
Hill Reaction ◽  
Amaranthus Hybridus ◽  
Apparent Affinity ◽  
Photosynthetic Electron Flow ◽  
Different Characteristics ◽  
The Hill

The reactivation of the Hill reaction in CO2-depleted broken chloroplasts by various concentrations of bicarbonate was measured in the absence and in the presence of photosystem II herbicides. It appears that these herbicides decrease the apparent affinity of the thylakoid membrane for bicarbonate. Different characteristics of bicarbonate binding were observed in chloroplasts of triazine-resistant Amaranthus hybridus compared to the triazine-sensitive biotype. It is concluded that photosystem II herbicides, bicarbonate and formate interact with each other in their binding to the Qв-protein and their interference with photosynthetic electron transport.

Glyphosate Does Not Inhibit Photosynthetic Electron Transport and Phosphorylation in Pea (Pisum sativum) Chloroplasts

Weed Science ◽  
1979 ◽  
Vol 27 (6) ◽  
pp. 684-688 ◽  
Author(s):  
E. P. Richard ◽  
J. R. Goss ◽  
C. J. Arntzen
Keyword(s):  
Electron Transport ◽  
Pisum Sativum ◽  
Photosynthetic Electron Transport ◽  
Photochemical Reactions ◽  
Transport Processes ◽  
Ps Ii ◽  
Dark Incubation ◽  
Fluorescence Studies ◽  
Mixture Prior

The activity of glyphosate [N-(phosphonomethyl)glycine], formulated as the isopropylamine salt, on in vitro photosynthesis was investigated. When pH 4.7 glyphosate solutions were titrated to a pH equal to that of the reaction media (pH 7.8), glyphosate additions had no effect on whole chain electron transport between coupled photosystem II (PS II) and photosystem I (PS I) in stroma-free chloroplast thylakoids from peas (Pisum sativumL. ‘Morse's Progress No. 9′). Inhibition did not occur even after a 2-h dark incubation of lamellae in a 5-mM solution of glyphosate. Fluorescence studies failed to detect an effect of glyphosate on PS-II mediated electron transport processes or upon light harvesting properties of PS II even after a 2-h glyphosate/chloroplast preincubation. Glyphosate had no effect on cyclic and noncyclic photophosphorylation even after a 100-min dark incubation of chloroplast membranes in a 5-mM solution of glyphosate. Based on these assays it is concluded that glyphosate has no direct effect on the photochemical reactions of photosynthesis when the pH of the active compound is adjusted to that of the reaction mixture prior to addition to a chloroplast suspension.

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.

Inhibition by Tetranitromethane of Photosynthetic Electron Transport from Water to Photosystem II in Chloroplasts

1980 ◽  
Vol 35 (3-4) ◽  
pp. 293-297 ◽  
Author(s):  
P. V. Sane ◽  
Udo Johanningmeier
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Electron Flow ◽  
Ph Dependence ◽  
Photosynthetic Electron Transport ◽  
Donor Side ◽  
Ps Ii ◽  
Diphenyl Carbazide ◽  
Low Concentrations ◽  
Sh Group

Abstract Low concentrations (10 µM) of tetranitromethane inhibit noncyclic electron transport in spinach chloroplasts. A study of different partial electron transport reactions shows that tetranitromethane primarily interferes with the electron flow from water to PS II. At higher concentrations the oxidation of plastohydroquinone is also inhibited. Because diphenyl carbazide but not Mn2+ ions can donate electrons efficiently to PS II in the presence of tetranitromethane it is suggested that it blocks the donor side of PS II prior to donation of electrons by diphenyl carbazide. The pH dependence of the inhibition by this protein modifying reagent may indicate that a functional-SH group is essential for a protein, which mediates electron transport between the water splitting complex and the reaction center of PS II.

scholarly journals Photosynthesis Regulation in Response to Fluctuating Light in the Secondary Endosymbiont Alga Nannochloropsis gaditana

2019 ◽  
Vol 61 (1) ◽  
pp. 41-52 ◽  
Author(s):  
Alessandra Bellan ◽  
Francesca Bucci ◽  
Giorgio Perin ◽  
Alessandro Alboresi ◽  
Tomas Morosinotto
Keyword(s):  
Electron Transport ◽  
Electron Flow ◽  
Incident Light ◽  
Photosynthetic Apparatus ◽  
Photosynthetic Electron Transport ◽  
Thermal Dissipation ◽  
Photochemical Quenching ◽  
Nannochloropsis Gaditana ◽  
Fluctuating Light ◽  
Light Fluctuations

Abstract In nature, photosynthetic organisms are exposed to highly dynamic environmental conditions where the excitation energy and electron flow in the photosynthetic apparatus need to be continuously modulated. Fluctuations in incident light are particularly challenging because they drive oversaturation of photosynthesis with consequent oxidative stress and photoinhibition. Plants and algae have evolved several mechanisms to modulate their photosynthetic machinery to cope with light dynamics, such as thermal dissipation of excited chlorophyll states (non-photochemical quenching, NPQ) and regulation of electron transport. The regulatory mechanisms involved in the response to light dynamics have adapted during evolution, and exploring biodiversity is a valuable strategy for expanding our understanding of their biological roles. In this work, we investigated the response to fluctuating light in Nannochloropsis gaditana, a eukaryotic microalga of the phylum Heterokonta originating from a secondary endosymbiotic event. Nannochloropsis gaditana is negatively affected by light fluctuations, leading to large reductions in growth and photosynthetic electron transport. Exposure to light fluctuations specifically damages photosystem I, likely because of the ineffective regulation of electron transport in this species. The role of NPQ, also assessed using a mutant strain specifically depleted of this response, was instead found to be minor, especially in responding to the fastest light fluctuations.

Mode of Inhibition of Photosynthetic Electron Transport by Substituted Diphenylethers

1981 ◽  
Vol 36 (9-10) ◽  
pp. 848-852 ◽  
Author(s):  
W. Draber ◽  
H. J. Knops ◽  
A. Trebst
Keyword(s):  
Electron Transport ◽  
Electron Flow ◽  
Photosynthetic Electron Transport ◽  
Thylakoid Membranes ◽  
Photosynthetic Electron Flow ◽  
Spinach Chloroplasts

Abstract Several substituted diphenylethers were found to be effective inhibitors of photosynthetic electron flow in isolated thylakoid membranes from spinach chloroplasts. T heir site of inhibition was localized with artificial acceptor and donor systems. The phenylether of an alkyl substituted nitrophenol is prim arely inhibiting electron flow after plastoquinone function whereas a dinitro-phenylether of a phenyl substituted nitrophenol is inhibiting before plastoquinone function. Therefore certain diphenylethers interfere with plastoquinone function at the oxidation or reduction site, depending on the substitution.

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