scholarly journals Dynamic Changes in Protein-Membrane Association for Regulating Photosynthetic Electron Transport

Cells ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1216
Author(s):  
Marine Messant ◽  
Anja Krieger-Liszkay ◽  
Ginga Shimakawa
Keyword(s):  
Electron Transport ◽  
Thylakoid Membrane ◽  
Electron Flow ◽  
Photosynthetic Apparatus ◽  
Photosynthetic Electron Transport ◽  
Thermal Dissipation ◽  
State Transitions ◽  
Photochemical Quenching ◽  
Damage Repair ◽  
Photosynthetic Organism

Photosynthesis has to work efficiently in contrasting environments such as in shade and full sun. Rapid changes in light intensity and over-reduction of the photosynthetic electron transport chain cause production of reactive oxygen species, which can potentially damage the photosynthetic apparatus. Thus, to avoid such damage, photosynthetic electron transport is regulated on many levels, including light absorption in antenna, electron transfer reactions in the reaction centers, and consumption of ATP and NADPH in different metabolic pathways. Many regulatory mechanisms involve the movement of protein-pigment complexes within the thylakoid membrane. Furthermore, a certain number of chloroplast proteins exist in different oligomerization states, which temporally associate to the thylakoid membrane and modulate their activity. This review starts by giving a short overview of the lipid composition of the chloroplast membranes, followed by describing supercomplex formation in cyclic electron flow. Protein movements involved in the various mechanisms of non-photochemical quenching, including thermal dissipation, state transitions and the photosystem II damage–repair cycle are detailed. We highlight the importance of changes in the oligomerization state of VIPP and of the plastid terminal oxidase PTOX and discuss the factors that may be responsible for these changes. Photosynthesis-related protein movements and organization states of certain proteins all play a role in acclimation of the photosynthetic organism to the environment.

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.

Bicarbonate utilization and pH polarity. The response of photosynthetic electron transport to carbon limitation in Potamogeton lucens leaves

1998 ◽  
Vol 76 (6) ◽  
pp. 1018-1024
Author(s):  
Lucina C van Ginkel ◽  
Hidde BA Prins
Keyword(s):  
Electron Transport ◽  
Carbon Source ◽  
Chlorophyll A ◽  
Redox Regulation ◽  
Photosynthetic Electron Transport ◽  
High Light ◽  
State Transitions ◽  
Photochemical Quenching ◽  
Carbon Limitation ◽  
Bicarbonate Utilization

By the process of pH polarity, several submersed angiosperms can use bicarbonate as carbon source for photosynthesis. Under conditions of relatively high light intensity and low CO2 availability, the pH of the apoplast and unstirred layer becomes acid at one side of the leaf and alkaline at the other. In the acid region, bicarbonate is converted into CO2, which diffuses into the leaf where it is fixed. Previous experiments on the light-dependent reduction of extracellular electron acceptors led to the hypothesis of redox regulation. Under conditions of high light and low CO2, excess reducing power in the chloroplast was supposed to be shuttled to the cytoplasm where it can upregulate the plasma membrane proton pump, leading to activation of polarity. Chlorophyll a fluorescence is an indicator for photosynthetic electron transport, the energization of thylakoids, and the reoxidation of chloroplast NADPH. It was used therefore to test redox regulation in vivo in Potamogeton lucens L. leaves. The fluoresence parameter, qP, an indicator for photochemical quenching and NADPH reoxidation, appeared to be rather insensitive to the inorganic carbon concentration and to the presence or absence of polarity. In contrast, qN, an indicator for non-photochemical quenching related to thylakoid energization, photoinhibition, and state transitions, increased under conditions of low CO2 - high light and polarity. Taken together the data show polarity to be an effective mechanism to make bicarbonate accessible as carbon source and seem to agree with the idea of redox regulation of pH polarity.Key words: bicarbonate utilization, chlorophyll a fluoresence, pH polarity, redox regulation, Potamogeton lucens, submerged aquatic macrophyte.

scholarly journals Differences in the photosynthetic and physiological responses of Leymus chinensis to different levels of grazing intensity

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Min Liu ◽  
Jirui Gong ◽  
Bo Yang ◽  
Yong Ding ◽  
Zihe Zhang ◽  
...  
Keyword(s):  
Electron Transport ◽  
Photosynthetic Capacity ◽  
Photosynthetic Apparatus ◽  
Chloroplast Ultrastructure ◽  
Grazing Intensity ◽  
Photosynthetic Electron Transport ◽  
Thermal Dissipation ◽  
Leymus Chinensis ◽  
Heavy Grazing ◽  
Grazing Intensities

Abstract Background Grazing is an important land use in northern China. In general, different grazing intensities had a different impact on the morphological and physiological traits of plants, and especially their photosynthetic capacity. We investigated the responses of Leymus chinensis to light, medium, and heavy grazing intensities in comparison with a grazing exclusion control. Results With light grazing, L. chinensis showed decreased photosynthetic capacity. The low chlorophyll and carotenoid contents constrained light energy transformation and dissipation, and Rubisco activity was also low, restricting the carboxylation efficiency. In addition, the damaged photosynthetic apparatus accumulated reactive oxygen species (ROS). With medium grazing, more energy was used for thermal dissipation, with high carotene content and high non-photochemical quenching, whereas photosynthetic electron transport was lowest. Significantly decreased photosynthesis decreased leaf C contents. Plants decreased the risk caused by ROS through increased energy dissipation. With high grazing intensity, plants changed their strategy to improve survival through photosynthetic compensation. More energy was allocated to photosynthetic electron transport. Though heavy grazing damaged the chloroplast ultrastructure, adjustment of internal mechanisms increased compensatory photosynthesis, and an increased tiller number facilitated regrowth after grazing. Conclusions Overall, the plants adopted different strategies by adjusting their metabolism and growth in response to their changing environment.

Plastoquinones in photosynthesis

1978 ◽  
Vol 284 (1002) ◽  
pp. 591-599 ◽  
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Energy Conservation ◽  
Thylakoid Membrane ◽  
Electron Flow ◽  
Proton Translocation ◽  
Photosynthetic Electron Transport ◽  
Atp Formation ◽  
Electron Transport Chains

Several plastoquinones with different or modified side chains have been characterized in plant material: they are localized in the inner thylakoid membrane of the chloroplast. So far only plastoquinone-45 (PQ-45) has been identified as an obligatory functional component of the photosynthetic electron transport chain in chloroplasts between photosystem II and photosystem I. A special form (semiquinone) of PQ-45 acts as primary acceptor Q of photosystem II, a large pool of PQ-45 as electron buffer, interconnecting several electron transport chains. The rôle of PQ, in energy conservation (ATP formation) is of particular current interest. Owing to vectorial electron flow across the thylakoid membrane, plastoquinone is thought to be reduced on the outside and plastohydroquinone to be oxidized on the inside of the membrane. This results in a proton translocation across the membrane and a build-up of a proton motive force which drives ATP formation. Old and new plastoquinone antagonists are described and the relevance of inhibitor studies on the rôle of plastoquinone in electron flow and photophosphorylation is discussed. Open questions and current problems of the mechanism of plastoquinone/plastoquinol transport across the membrane - and of proton translocation connected to it - relevant for the mechanism of energy conservation in photosynthesis, are pointed out.

Macroorganisation and flexibility of thylakoid membranes

2019 ◽  
Vol 476 (20) ◽  
pp. 2981-3018 ◽  
Author(s):  
Petar H. Lambrev ◽  
Parveen Akhtar
Keyword(s):  
Light Harvesting ◽  
Current Knowledge ◽  
Three Dimensional ◽  
Photosynthetic Apparatus ◽  
Dynamic Responses ◽  
State Transitions ◽  
Photochemical Quenching ◽  
Light Harvesting Complex ◽  
Complex Ii ◽  
Light Harvesting Complex Ii

Abstract The light reactions of photosynthesis are hosted and regulated by the chloroplast thylakoid membrane (TM) — the central structural component of the photosynthetic apparatus of plants and algae. The two-dimensional and three-dimensional arrangement of the lipid–protein assemblies, aka macroorganisation, and its dynamic responses to the fluctuating physiological environment, aka flexibility, are the subject of this review. An emphasis is given on the information obtainable by spectroscopic approaches, especially circular dichroism (CD). We briefly summarise the current knowledge of the composition and three-dimensional architecture of the granal TMs in plants and the supramolecular organisation of Photosystem II and light-harvesting complex II therein. We next acquaint the non-specialist reader with the fundamentals of CD spectroscopy, recent advances such as anisotropic CD, and applications for studying the structure and macroorganisation of photosynthetic complexes and membranes. Special attention is given to the structural and functional flexibility of light-harvesting complex II in vitro as revealed by CD and fluorescence spectroscopy. We give an account of the dynamic changes in membrane macroorganisation associated with the light-adaptation of the photosynthetic apparatus and the regulation of the excitation energy flow by state transitions and non-photochemical quenching.

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.

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.

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