Regulation of chloroplast metabolism in leaves: Evidence that NADP-dependent glyceraldehydephosphate dehydrogenase, but not ferredoxin-NADP reductase, controls electron flow to phosphoglycerate in the dark-light transition

Planta ◽  
1991 ◽  
Vol 185 (3) ◽  
Author(s):  
Katharina Siebke ◽  
Agu Laisk ◽  
Spidola Neimanis ◽  
Ulrich Heber
Keyword(s):  
Electron Flow ◽  
Dark Light ◽  
Chloroplast Metabolism ◽  
Glyceraldehydephosphate Dehydrogenase

scholarly journals Light-Dependent Regulation of Cyanobacterial Phytochrome Expression

2000 ◽  
Vol 182 (1) ◽  
pp. 38-44 ◽  
Author(s):  
M. García-Domínguez ◽  
M. I. Muro-Pastor ◽  
J. C. Reyes ◽  
F. J. Florencio
Keyword(s):  
Response Regulator ◽  
Electron Flow ◽  
Spectral Characteristics ◽  
Red Light ◽  
Mrna Levels ◽  
Two Component System ◽  
Dark Light ◽  
Transcript Stability ◽  
Normal Light

ABSTRACT A histidine kinase protein (Cph1) with sequence homology and spectral characteristics very similar to those of the plant phytochrome has been recently identified in the cyanobacteriumSynechocystis sp. strain PCC 6803. Cph1 together with Rcp1 (a protein homologue to the response regulator CheY) forms a light-regulated two-component system whose function is presently unknown. Levels of cph1 rcp1 mRNA increase in the dark and decrease upon reillumination. A dark-mediated increase in cph1 rcp1 mRNA levels was inhibited by the presence of glucose, but not by inhibition of the photosynthetic electron flow. The half-life ofcph1 rcp1 transcript in the light was about fourfold shorter than in the dark, indicating that control of cph1 rcp1 transcript stability is one of the mechanisms by which light regulates expression of the cyanobacterial phytochrome. After 15 min of darkness, 3-min pulses of red, blue, green, and far-red light were equally efficient in decreasing the cph1 rcp1 mRNA levels. Red light downregulation was not reversed by far-red light, suggesting that cph1 rcp1 mRNA levels are not controlled by a phytochrome-like photoreceptor. Furthermore, aSynechocystis strain containing an H538R Cph1 point mutation, unable to phosphorylate Rcp1, shows normal light-dark regulation of the cph1 rcp1 transcript levels. Our data suggest a role of cyanobacterial phytochrome in the control of processes required for adaptation in light-dark and dark-light transitions.

scholarly journals Glycogen metabolism jump-starts photosynthesis through the oxidative pentose phosphate pathway (OPPP) in cyanobacteria

2019 ◽  
Author(s):  
Shrameeta Shinde ◽  
Sonali P. Singapuri ◽  
Xiaohui Zhang ◽  
Isha Kalra ◽  
Xianhua Liu ◽  
...  
Keyword(s):  
Pentose Phosphate Pathway ◽  
Carbon Fixation ◽  
Transition Period ◽  
Dark Respiration ◽  
Electron Flow ◽  
Glycogen Metabolism ◽  
Pentose Phosphate ◽  
Oxidative Pentose Phosphate Pathway ◽  
Cellular Respiration ◽  
Dark Light

AbstractCyanobacteria experience drastic changes in their carbon metabolism under daily light-dark cycles. In the light, the Calvin-Benson cycle fixes CO2and divert excess carbon into glycogen storage. At night, glycogen is degraded to support cellular respiration. Dark-light transition represents a universal environmental stress for cyanobacteria and other photosynthetic lifeforms. Recent studies in the field revealed the essential genetic background necessary for the fitness of cyanobacteria during diurnal growth. However, the metabolic engagement behind the dark-light transition is not well understood. In this study, we discovered that glycogen metabolism can jump-start photosynthesis in the cyanobacteriumSynechococcus elongatusPCC 7942 when photosynthesis reactions start upon light. Compared to the wild type, the glycogen mutant (ΔglgC) showed much lower photosystem II efficiency and slower photosystem I-mediated cyclic electron flow rate when photosynthesis starts. Proteomics analyses indicated that glycogen is degraded through the oxidative pentose phosphate pathway (OPPP) during dark-light transition. We confirmed that the OPPP is essential for the initiation of photosynthesis, and further showed that glycogen degradation through the OPPP is likely to contribute to the activation of key Calvin-Benson cycle enzymes by modulating NADPH levels during the transition period. This ingenious strategy helps jump-start photosynthesis in cyanobacteria following dark respiration, and stabilize the Calvin-Benson cycle under fluctuating environmental conditions. It has evolutionary advantages for the survival of photosynthetic organisms using the Calvin-Benson cycle for carbon fixation.

scholarly journals Effects of light / dark diel cycles on the photoorganoheterotrophic metabolism of Rhodopseudomonas palustris for differential electron allocation to PHAs and H2

2020 ◽  
Author(s):  
Marta Cerruti ◽  
Heleen T. Ouboter ◽  
Viktor Chasna ◽  
Mark C. M. van Loosdrecht ◽  
Cristian Picioreanu ◽  
...  
Keyword(s):  
Electron Flow ◽  
Rhodopseudomonas Palustris ◽  
Purple Sulfur Bacteria ◽  
Dark Phase ◽  
Substrate Uptake ◽  
Dark Light ◽  
Intermittent Light ◽  
Diel Cycles ◽  
Sulfur Bacteria ◽  
Metabolic Versatility

AbstractLight/dark cycles can impact the electron distribution in Rhodopseudomonas palustris, a hyperversatile photoorganoheterotrophic purple non-sulfur bacterium (PNSB). Dynamic conditions during diel cycles are important for the physiology of PNSB, but the coupling between illumination patterns and redox balancing has not been extensively studied. For survival and growth, Rhodopseudomonas has developed different mechanisms to allocate electrons under dynamic growth conditions. Products such as hydrogen and poly-β-hydroxyalkanoates (PHAs) can form alternative electron sinks. A continuous culture, fed with a balanced nutrients medium, was exposed to three different conditions: 24 h continuous infrared illumination, 16h light/8h dark, and 8h light/16h dark. Light and dark phase durations in a cycle determined the energy availability level (light) and the attainment of a stationary state. Under long dark phases, the acetate substrate accumulated to levels that could not be depleted by growth in the light. Under short dark phases, acetate was rapidly consumed in the light with most of the phototrophic growth occurring under acetate-limiting conditions. Under diel cycles, substrate uptake and growth were unbalanced and Rhodopseudomonas shunted the excess of carbon and electron flow first toward PHAs production. Only secondarily, when PHA storage got saturated, the electron excess was redirected toward H2. A numerical model described well the dynamics of biomass and nutrients during the different light/dark cycle regimes. The model simulations allowed determination of stoichiometric and kinetic parameters for conversion by Rhodopseudomonas. Understanding the inherent process dynamics of diel light cycles in purple sulfur bacteria cultures would enable optimization procedures for targeted bioproduct formation.ImportancePurple non-sulfur bacteria (PNSB) are important anoxygenic phototrophic microorganisms that take part in numerous environmental processes, based on their metabolic versatility. Rhodopseudomonas palustris is a model photosynthetic bacterium of the PNSB guild. Light cycles influence deeply its physiology. Poly-β-hydroxyalkanoates (PHAs) and biohydrogen are two of the most studied metabolic products of Rhodopseudomonas, because of their biotechnology potential besides involvement in carbon and electron allocations in its metabolism. Their production mechanisms have often been described as competitive, but the rationale behind the production of one or the other compound has not been elucidated. Here, we found that under light / dark cycles an excess of organic substrate was first directed toward PHAs production, and only when this pathway was saturated H2 was produced. Understanding the dynamics of carbon and electron allocation under intermittent light cycles enhances our knowledge on PNSB metabolisms and paves ways to manage the formation of targeted bioproducts.

Subcellular compartmentation of pyrophosphate and dark/light kinetics in comparison to fructose 2,6-bisphosphate

1992 ◽  
Vol 84 (1) ◽  
pp. 13-20 ◽  
Author(s):  
Dagmar Eberl ◽  
Manuela Preissler ◽  
Manfred Steingraber ◽  
Rudiger Hampp
Keyword(s):  
Dark Light ◽  
Subcellular Compartmentation

Bio-Inspired Submicron Electrodes

2003 ◽  
Vol 775 ◽  
Author(s):  
Ivan Stanish ◽  
Daniel A. Lowy ◽  
Alok Singh
Keyword(s):  
Electrode Surface ◽  
Structural Integrity ◽  
Electron Flow ◽  
Charge Storage ◽  
Electroactive Material ◽  
Electron Coupling ◽  
Strong Potential ◽  
Electrical Potentials ◽  
Submicron Scale ◽  
Potential Gradients

AbstractImmobilized polymerized electroactive vesicles (IPEVs) are submicron biocapsules capable of storing charge in confined environments and chemisorbing on surfaces. Methods to immobilize stable submicron sized electroactive vesicles and the means to measure electroactivity of IPEVs at nanolevels have been demonstrated. IPEVs can withstand steep potential gradients applied across their membrane, maintain their structural integrity against surfaces poised at high/low electrical potentials, retain electroactive material over several days, and reversibly mediate (within the membrane) electron flow between the electrode surface and vesicle interior. IPEVs have strong potential to be used for charge storage and electron coupling applications that operate on the submicron scale and smaller.

1606-P: Effect of Changes in Dark/Light Cycle on Physiological Homeostasis as a Confounding Prelude to Diabetes in Fischer 334 Animal Model

Diabetes ◽  
2020 ◽  
Vol 69 (Supplement 1) ◽  
pp. 1606-P
Author(s):  
BALANEHRU SUBRAMANIAN ◽  
GANAPATHY RAMAKRISHNAN ◽  
PANNERSELVAM TAMILMARAN ◽  
BALAKRISHNAN SUNDARAKRISHNAN ◽  
KRISHNA SESHADRI
Keyword(s):  
Animal Model ◽  
Light Cycle ◽  
Dark Light ◽  
Physiological Homeostasis

Crop Growth Influenced by Repeat of Bright-dark Light (II)

1983 ◽  
Vol 39 (2) ◽  
pp. 97-101 ◽  
Author(s):  
Haruo SUZUKI ◽  
Yoshikazu KANBATA ◽  
Koichi MIYAMOTO
Keyword(s):  
Crop Growth ◽  
Dark Light

Physiological Role of Cyclic Electron Flow in Higher Plants

2012 ◽  
Vol 30 (1) ◽  
pp. 100
Author(s):  
Wei HUANG ◽  
Shi-Bao ZHANG ◽  
Kun-Fang CAO
Keyword(s):  
Higher Plants ◽  
Electron Flow ◽  
Physiological Role ◽  
Cyclic Electron Flow
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