scholarly journals A novel method produces native light-harvesting complex II aggregates from the photosynthetic membrane revealing their role in nonphotochemical quenching

2020 ◽  
Vol 295 (51) ◽  
pp. 17816-17826
Author(s):  
Mahendra K. Shukla ◽  
Akimasa Watanabe ◽  
Sam Wilson ◽  
Vasco Giovagnetti ◽  
Ece Imam Moustafa ◽  
...  
Keyword(s):  
Light Harvesting ◽  
Higher Plants ◽  
Photosynthetic Apparatus ◽  
Preparative Method ◽  
Nonphotochemical Quenching ◽  
Photosynthetic Membrane ◽  
Purification Method ◽  
Ps Ii ◽  
Core Proteins

Nonphotochemical quenching (NPQ) is a mechanism of regulating light harvesting that protects the photosynthetic apparatus from photodamage by dissipating excess absorbed excitation energy as heat. In higher plants, the major light-harvesting antenna complex (LHCII) of photosystem (PS) II is directly involved in NPQ. The aggregation of LHCII is proposed to be involved in quenching. However, the lack of success in isolating native LHCII aggregates has limited the direct interrogation of this process. The isolation of LHCII in its native state from thylakoid membranes has been problematic because of the use of detergent, which tends to dissociate loosely bound proteins, and the abundance of pigment–protein complexes (e.g. PSI and PSII) embedded in the photosynthetic membrane, which hinders the preparation of aggregated LHCII. Here, we used a novel purification method employing detergent and amphipols to entrap LHCII in its natural states. To enrich the photosynthetic membrane with the major LHCII, we used Arabidopsis thaliana plants lacking the PSII minor antenna complexes (NoM), treated with lincomycin to inhibit the synthesis of PSI and PSII core proteins. Using sucrose density gradients, we succeeded in isolating the trimeric and aggregated forms of LHCII antenna. Violaxanthin- and zeaxanthin-enriched complexes were investigated in dark-adapted, NPQ, and dark recovery states. Zeaxanthin-enriched antenna complexes showed the greatest amount of aggregated LHCII. Notably, the amount of aggregated LHCII decreased upon relaxation of NPQ. Employing this novel preparative method, we obtained a direct evidence for the role of in vivo LHCII aggregation in NPQ.

scholarly journals pH dependence, kinetics and light-harvesting regulation of nonphotochemical quenching inChlamydomonas

2019 ◽  
Vol 116 (17) ◽  
pp. 8320-8325 ◽  
Author(s):  
Lijin Tian ◽  
Wojciech J. Nawrocki ◽  
Xin Liu ◽  
Iryna Polukhina ◽  
Ivo H. M. van Stokkum ◽  
...  
Keyword(s):  
Light Harvesting ◽  
Ph Dependence ◽  
Ph Sensor ◽  
Complex Stress ◽  
Nonphotochemical Quenching ◽  
Ps Ii ◽  
Light Harvesting Complex ◽  
Photosynthetic Organisms

Sunlight drives photosynthesis but can also cause photodamage. To protect themselves, photosynthetic organisms dissipate the excess absorbed energy as heat, in a process known as nonphotochemical quenching (NPQ). In green algae, diatoms, and mosses, NPQ depends on the light-harvesting complex stress-related (LHCSR) proteins. Here we investigated NPQ inChlamydomonas reinhardtiiusing an approach that maintains the cells in a stable quenched state. We show that in the presence of LHCSR3, all of the photosystem (PS) II complexes are quenched and the LHCs are the site of quenching, which occurs at a rate of ∼150 ps−1and is not induced by LHCII aggregation. The effective light-harvesting capacity of PSII decreases upon NPQ, and the NPQ rate is independent of the redox state of the reaction center. Finally, we could measure the pH dependence of NPQ, showing that the luminal pH is always above 5.5 in vivo and highlighting the role of LHCSR3 as an ultrasensitive pH sensor.

scholarly journals The role of inactive photosystem–II–mediated quenching in a last–ditch community defence against high light stress in vivo

2002 ◽  
Vol 357 (1426) ◽  
pp. 1441-1450 ◽  
Author(s):  
Wah Soon Chow ◽  
Hae–Youn Lee ◽  
Youn–Il Park ◽  
Yong–Mok Park ◽  
Yong–Nam Hong ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Light Stress ◽  
Extreme Environments ◽  
Photosynthetic Apparatus ◽  
Optimal Operation ◽  
Residual Fraction ◽  
Photosynthetic Membrane ◽  
Number Of Factors ◽  
Inactive Photosystem Ii

Photoinactivation of photosystem II (PSII), the light–induced loss of ability to evolve oxygen, is an inevitable event during normal photosynthesis, exacerbated by saturating light but counteracted by repair via new protein synthesis. The photoinactivation of PSII is dependent on the dosage of light: in the absence of repair, typically one PSII is photoinactivated per 10 7 photons, although the exact quantum yield of photoinactivation is modulated by a number of factors, and decreases as fewer active PSII targets are available. PSII complexes initially appear to be photoinactivated independently; however, when less than 30% functional PSII complexes remain, they seem to be protected by strongly dissipative PSII reaction centres in several plant species examined so far, a mechanism which we term ‘inactive PSII–mediated quenching‘. This mechanism appears to require a pH gradient across the photosynthetic membrane for its optimal operation. The residual fraction of functional PSII complexes may, in turn, aid in the recovery of photoinactivated PSII complexes when conditions become less severe. This mechanism may be important for the photosynthetic apparatus in extreme environments such as those experienced by over–wintering evergreen plants, desert plants exposed to drought and full sunlight and shade plants in sustained sunlight.

scholarly journals Photosynthetic apparatus of purple bacteria

2002 ◽  
Vol 35 (1) ◽  
pp. 1-62 ◽  
Author(s):  
Xiche Hu ◽  
Thorsten Ritz ◽  
Ana Damjanović ◽  
Felix Autenrieth ◽  
Klaus Schulten
Keyword(s):  
Photosynthetic Bacteria ◽  
Higher Plants ◽  
Purple Bacteria ◽  
Photosynthetic Apparatus ◽  
Excitation Transfer ◽  
Oxygenic Photosynthesis ◽  
Photosynthetic Reaction Centers ◽  
Primary Charge Separation ◽  
Photosynthetic Membrane ◽  
Light Harvesting Complexes

1. Introduction 22. Structure of the bacterial PSU 52.1 Organization of the bacterial PSU 52.2 The crystal structure of the RC 92.3 The crystal structures of LH-II 112.4 Bacteriochlorophyll pairs in LH-II and the RC 132.5 Models of LH-I and the LH-I-RC complex 152.6 Model for the PSU 173. Excitation transfer in the PSU 183.1 Electronic excitations of BChls 22 3.1.1 Individual BChls 22 3.1.2 Rings of BChls 22 3.1.2.1 Exciton states 22 3.1.3 Effective Hamiltonian 24 3.1.4 Optical properties 25 3.1.5 The effect of disorder 263.2 Theory of excitation transfer 29 3.2.1 General theory 29 3.2.2 Mechanisms of excitation transfer 32 3.2.3 Approximation for long-range transfer 34 3.2.4 Transfer to exciton states 353.3 Rates for transfer processes in the PSU 37 3.3.1 Car→BChl transfer 37 3.3.1.1 Mechanism of Car→BChl transfer 39 3.3.1.2 Pathways of Car→BChl transfer 40 3.3.2 Efficiency of Car→BChl transfer 40 3.3.3 B800-B850 transfer 44 3.3.4 LH-II→LH-II transfer 44 3.3.5 LH-II→LH-I transfer 45 3.3.6 LH-I→RC transfer 45 3.3.7 Excitation migration in the PSU 46 3.3.8 Genetic basis of PSU assembly 494. Concluding remarks 535. Acknowledgments 556. References 55Life as we know it today exists largely because of photosynthesis, the process through which light energy is converted into chemical energy by plants, algae, and photosynthetic bacteria (Priestley, 1772; Barnes, 1893; Wurmser, 1925; Van Niel, 1941; Clayton & Sistrom, 1978; Blankenship et al. 1995; Ort & Yocum, 1996). Historically, photosynthetic organisms are grouped into two classes. When photosynthesis is carried out in the presence of air it is called oxygenic photosynthesis (Ort & Yocum, 1996). Otherwise, it is anoxygenic (Blankenship et al. 1995). Higher plants, algae and cyanobacteria perform oxygenic photosynthesis, which involves reduction of carbon dioxide to carbohydrate and oxidation of water to produce molecular oxygen. Some photosynthetic bacteria, such as purple bacteria, carry out anoxygenic photosynthesis that involves oxidation of molecules other than water. In spite of these differences, the general principles of energy transduction are the same in anoxygenic and oxygenic photosynthesis (Van Niel, 1931, 1941; Stanier, 1961; Wraight, 1982; Gest, 1993). The primary processes of photosynthesis involve absorption of photons by light-harvesting complexes (LHs), transfer of excitation energy from LHs to the photosynthetic reaction centers (RCs), and the primary charge separation across the photosynthetic membrane (Sauer, 1975; Knox, 1977; Fleming & van Grondelle, 1994; van Grondelle et al. 1994). In this article, we will focus on the anoxygenic photosynthetic process in purple bacteria, since its photosynthetic system is the most studied and best characterized during the past 50 years.

scholarly journals Marine Cyanobacteria Tune Energy Transfer Efficiency in their Light-harvesting Antennae by Modifying Pigment Coupling

2019 ◽  
Author(s):  
Yuval Kolodny ◽  
Hagit Zer ◽  
Mor Propper ◽  
Shira Yochelis ◽  
Yossi Paltiel ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Light Harvesting ◽  
Vertical Mixing ◽  
Photosynthetic Apparatus ◽  
Emission Spectra ◽  
Energy Transfer Efficiency ◽  
Transfer Efficiency ◽  
Transfer Energy ◽  
Harvesting Process

AbstractPhotosynthetic organisms regulate energy transfer to fit to changes in environmental conditions. The biophysical principles underlying the flexibility and efficiency of energy transfer in the light-harvesting process are still not fully understood. Here we examine how energy transfer is regulatedin-vivo. We compare different acclimation states of the photosynthetic apparatus in a marine cyanobacterial species that is well adapted to vertical mixing of the ocean water column and identify a novel acclimation strategy for photosynthetic life under low light intensities. Antennae rods extend, as expected, increasing light absorption. Surprisingly, in contrast to what was known for plants and predicted by classic calculations, these longer rods transfer energy fasteri.e.more efficiently. The fluorescence lifetime and emission spectra dependence on temperature, at the range of 4-300K, suggests that energy transfer efficiency is tuned by modifying the energetic coupling strength between antennae pigments.

scholarly journals The effect of chilling on the photosynthetic activity in coffee (Coffea arabica L.) seedlings: The protective action of chloroplastid pigments

2002 ◽  
Vol 14 (2) ◽  
pp. 95-104 ◽  
Author(s):  
Jurandi Gonçalves de Oliveira ◽  
Pedro Luis C.A. Alves ◽  
Antonio Celso Magalhães
Keyword(s):  
Low Temperatures ◽  
Coffea Arabica ◽  
Structural Integrity ◽  
Photosynthetic Activity ◽  
Protective Action ◽  
Photosynthetic Apparatus ◽  
Photochemical Reactions ◽  
Tissue Storage ◽  
Ps Ii

Coffea arabica is considered to be sensitive to low temperatures, being affected throughout its entire life cycle. Injury caused by chilling (low temperatures above zero degree centigrade) is characterized primarily by inhibition of the photosynthetic process. The objective of this work was to evaluate the role of photosynthetic pigments in the tolerance of coffee (C. arabica L.) seedlings to chilling. The evaluation the photosynthetic activity was made by emission of Chl a fluorescence at room temperature (25 ºC) in vivo and in situ, using a portable fluorometer. The pigment content was obtained by extraction with 80 % acetone, while estimation of membrane lipid peroxidation was determined by measuring the MDA content in leaf tissue extracts. The results indicated a generalized reduction in the quantum yield of PSII when the seedlings were maintained in the dark. The reduction occurred in the seedlings submitted to chilling treatment as well as in the control ones. This demonstrates that not only chilling acts to cause an alteration in PSII. It is possible that the tissue storage reserves had been totally exhausted, with the respiratory rate exceeding the photosynthetic rate; the later was nil, since the seedlings were kept in the dark. The efficiency in the capture, transfer and utilization of light energy in PS II photochemical reactions requires a sequence of photochemical, biochemical and biophysical events which depend on the structural integrity of the photosynthetic apparatus. However, this efficiency was found to be related to the protective action of chloroplastid pigments, rather than to the concentration of these pigments.

scholarly journals Allosteric regulation of the light-harvesting system of photosystem II

2000 ◽  
Vol 355 (1402) ◽  
pp. 1361-1370 ◽  
Author(s):  
Peter Horton ◽  
Alexander V. Ruban ◽  
Mark Wentworth
Keyword(s):  
Photosystem Ii ◽  
Xanthophyll Cycle ◽  
Light Harvesting ◽  
Allosteric Regulation ◽  
Photochemical Quenching ◽  
Protein Subunit ◽  
Ps Ii ◽  
Non Photochemical Quenching

Non–photochemical quenching of chlorophyll fluorescence (NPQ) is symptomatic of the regulation of energy dissipation by the light–harvesting antenna of photosystem II (PS II). The kinetics of NPQ in both leaves and isolated chloroplasts are determined by the transthylakoid ΔpH and the de–epoxidation state of the xanthophyll cycle. In order to understand the mechanism and regulation of NPQ we have adopted the approaches commonly used in the study of enzyme–catalysed reactions. Steady–state measurements suggest allosteric regulation of NPQ, involving control by the xanthophyll cycle carotenoids of a protonationdependent conformational change that transforms the PS II antenna from an unquenched to a quenched state. The features of this model were confirmed using isolated light–harvesting proteins. Analysis of the rate of induction of quenching both in vitro and in vivo indicated a bimolecular second–order reaction; it is suggested that quenching arises from the reaction between two fluorescent domains, possibly within a single protein subunit. A universal model for this transition is presented based on simple thermodynamic principles governing reaction kinetics.

scholarly journals Phosphorylation of Light-harvesting Complex II and Photosystem II Core Proteins Shows Different Irradiance-dependent Regulation in Vivo

1997 ◽  
Vol 272 (48) ◽  
pp. 30476-30482 ◽  
Author(s):  
Eevi Rintamäki ◽  
Mervi Salonen ◽  
Ulla-Maija Suoranta ◽  
Inger Carlberg ◽  
Bertil Andersson ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Light Harvesting ◽  
Light Harvesting Complex ◽  
Complex Ii ◽  
Core Proteins ◽  
Light Harvesting Complex Ii

Dissipation of Light Energy Absorbed in Excess: The Molecular Mechanisms

2021 ◽  
Vol 72 (1) ◽  
pp. 47-76
Author(s):  
Roberto Bassi ◽  
Luca Dall'Osto
Keyword(s):  
Molecular Mechanisms ◽  
Light Harvesting ◽  
Photosynthetic Apparatus ◽  
Reaction Times ◽  
Time Of Day ◽  
Light Energy ◽  
Spectroscopic Techniques ◽  
Photosynthetic Organisms ◽  
Excess Light

Light is essential for photosynthesis. Nevertheless, its intensity widely changes depending on time of day, weather, season, and localization of individual leaves within canopies. This variability means that light collected by the light-harvesting system is often in excess with respect to photon fluence or spectral quality in the context of the capacity of photosynthetic metabolism to use ATP and reductants produced from the light reactions. Absorption of excess light can lead to increased production of excited, highly reactive intermediates, which expose photosynthetic organisms to serious risks of oxidative damage. Prevention and management of such stress are performed by photoprotective mechanisms, which operate by cutting down light absorption, limiting the generation of redox-active molecules, or scavenging reactive oxygen species that are released despite the operation of preventive mechanisms. Here, we describe the major physiological and molecular mechanisms of photoprotection involved in the harmless removal of the excess light energy absorbed by green algae and land plants. In vivo analyses of mutants targeting photosynthetic components and the enhanced resolution of spectroscopic techniques have highlighted specific mechanisms protecting the photosynthetic apparatus from overexcitation. Recent findings unveil a network of multiple interacting elements, the reaction times of which vary from a millisecond to weeks, that continuously maintain photosynthetic organisms within the narrow safety range between efficient light harvesting and photoprotection.

The lutein epoxide cycle in higher plants: its relationships to other xanthophyll cycles and possible functions

2007 ◽  
Vol 34 (9) ◽  
pp. 759 ◽  
Author(s):  
Jose I. García-Plazaola ◽  
Shizue Matsubara ◽  
C. Barry Osmond
Keyword(s):  
Light Harvesting ◽  
Higher Plants ◽  
Protein Complexes ◽  
Light Exposure ◽  
Photosynthetic Pigment ◽  
In Vivo Studies ◽  
Photochemical Quenching ◽  
Strong Light

Several xanthophyll cycles have been described in photosynthetic organisms. Among them, only two are present in higher plants: the ubiquitous violaxanthin (V) cycle, and the taxonomically restricted lutein epoxide (Lx) cycle, whereas four cycles seem to occur in algae. Although V is synthesised through the β-branch of the carotenoid biosynthetic pathway and Lx is the product of the α-branch; both are co-located in the same sites of the photosynthetic pigment-protein complexes isolated from thylakoids. Both xanthophylls are also de-epoxidised upon light exposure by the same enzyme, violaxanthin de-epoxidase (VDE) leading to the formation of zeaxanthin (Z) and lutein (L) at comparable rates. In contrast with VDE, the reverse reaction presumably catalysed by zeaxanthin epoxidase (ZE), is much slower (or even inactive) with L than with antheraxanthin (A) or Z. Consequently many species lack Lx altogether, and although the presence of Lx shows an irregular taxonomical distribution in unrelated taxa, it has a high fidelity at family level. In those plants which accumulate Lx, variations in ZE activity in vivo mean that a complete Lx-cycle occurs in some (with Lx pools being restored overnight), whereas in others a truncated cycle is observed in which VDE converts Lx into L, but regeneration of Lx by ZE is extremely slow. Accumulation of Lx to high concentrations is found most commonly in old leaves in deeply shaded canopies, and the Lx cycle in these leaves is usually truncated. This seemingly anomalous situation presumably arises because ZE has a low but finite affinity for L, and because deeply shaded leaves are not often exposed to light intensities strong enough to activate VDE. Notably, both in vitro and in vivo studies have recently shown that accumulation of Lx can increase the light harvesting efficiency in the antennae of PSII. We propose a model for the truncated Lx cycle in strong light in which VDE converts Lx to L which then occupies sites L2 and V1 in the light-harvesting antenna complex of PSII (Lhcb), displacing V and Z. There is correlative evidence that this photoconverted L facilitates energy dissipation via non-photochemical quenching and thereby converts a highly efficient light harvesting system to an energy dissipating system with improved capacity to engage photoprotection. Operation of the α- and β-xanthophyll cycles with different L and Z epoxidation kinetics thus allows a combination of rapidly and slowly reversible modulation of light harvesting and photoprotection, with each cycle having distinct effects. Based on the patchy taxonomical distribution of Lx, we propose that the presence of Lx (and the Lx cycle) could be the result of a recurrent mutation in the epoxidase gene that increases its affinity for L, which is conserved whenever it confers an evolutionary advantage.

scholarly journals Growth Improvement of Nicotiana and Arabidopsis In Vitro by Microalgal Conditioned Media

2015 ◽  
Vol 56 (2) ◽  
pp. 91-97 ◽  
Author(s):  
Elżbieta Zielińska ◽  
Krystyna Matusiak-Mikulin ◽  
Krzysztof Grabski ◽  
Anna Heda ◽  
Aleksandra Krzykowska ◽  
...  
Keyword(s):  
Higher Plants ◽  
Photosynthetic Apparatus ◽  
Dry Weight ◽  
General Term ◽  
Transport Efficiency ◽  
Desmodesmus Subspicatus ◽  
Whole Plants ◽  
Stimulation Of

Abstract Conditioned medium (CM) is a general term describing media in which cells have already been cultivated for some time. Such media, usually clarified by filtration, have been used by plant biotechnologists as additives sup-porting the growth of cell suspensions, organs and whole plants. This study examined the effect of CM obtained from green alga Desmodesmus subspicatus on the growth and functioning of the photosynthetic apparatus of Nicotiana tabacum and Arabidopsis thaliana in culture in vitro. Plants where cultured on CM diluted 1.25-, 2-and 5-fold with MS medium. The increase in fresh and dry weight was highest in tobacco and Arabidopsis cultured on CM/2 and CM/1.25 media. Those two concentrations also increased the amount of chlorophylls in both plants tested. CM improved parameter PI (reflecting the photosynthetic “vitality” of the organism) and electron transport efficiency, and increased the fraction of active reaction centers. Analysis of chlorophyll fluorescence in vivo suggests that the improvement of these plants grown in the presence of algal CM may result from stimulation of photosynthesis. Algal CM offers a convenient, cheap, universal supplement for stimulating the growth of higher plants in vitro.

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