scholarly journals Structure of the Quenched Cyanobacterial OCP-Phycobilisome Complex

2021 ◽  
Author(s):  
Maria Agustina Dominguez-Martin ◽  
Paul V Sauer ◽  
Markus Sutter ◽  
Henning Kirst ◽  
David Bina ◽  
...  
Keyword(s):  
Active Form ◽  
Light Energy ◽  
Structural Basis ◽  
Photochemical Quenching ◽  
Regulatory Domain ◽  
Dynamic Surface ◽  
Photosynthetic Organisms ◽  
Cryo Electron Microscopy ◽  
Orange Carotenoid Protein ◽  
Non Photochemical Quenching

Photoprotection is an essential mechanism in photosynthetic organisms to balance the harvesting of light energy against the risks of photodamage. In cyanobacteria, photoprotective non-photochemical quenching relies on the interaction between a photoreceptor, the Orange Carotenoid Protein (OCP), and the antenna, the phycobilisome (PBS). Here we report the first structure of the OCP-PBS complex at 2.7 Å overall resolution obtained by cryo-electron microscopy. The structure shows that the 6.2 MDa PBS is quenched by four 34 kDa OCP organized as two dimers. The complex also reveals that the structure of the active form of the OCP is drastically different than its resting, non-quenching form, with an ~60 Å displacement of its regulatory domain. These results provide a high-resolution blueprint of the structural basis of the protective quenching of excess excitation energy that enables cyanobacteria to harvest light energy and fix CO2 across environmentally diverse and dynamic surface of our planet.

Orange Carotenoid Protein (OCP): A Key Player in Non-photochemical Quenching of Cyanobacteria under Fluctuating Light Condition

2018 ◽  
Vol 4 (02) ◽  
pp. 35-40
Author(s):  
Yogesh Mishra ◽  
Akanksha Srivastava ◽  
Atul Tiwari ◽  
Raju Mondal ◽  
Sandhya Yadav ◽  
...  
Keyword(s):  
Active Form ◽  
Light Condition ◽  
High Irradiance ◽  
Water Soluble ◽  
Photochemical Quenching ◽  
Protective Mechanism ◽  
Terminal Domain ◽  
Fluctuating Light ◽  
Orange Carotenoid Protein ◽  
Non Photochemical Quenching

Fluctuating light condition poses major threat to photosynthetic organisms by evoking the production of reactive oxygen species (ROS). To endure the high irradiance level, plants and algae have evolved a photo-protective mechanism, referred as non-photochemical quenching (NPQ). This mechanism concerns with minimizing arrival of the excess excitation energy on reaction centers by dissipating surplus energy in form of harmless heat. Earlier cyanobacteria were not considered to capable of performing NPQ. Alternatively, state transition was supposed to be the major means that cyanobacteria preferably carried out to be protected under high light. Recently it was substantiated with evidence that these organisms can execute NPQ as a prominent photo-protective strategy. NPQ in cyanobacteria is mediated by a water soluble orange carotenoid protein (OCP) which is structurally and functionally modular. OCP consists of two domains (i) N-terminal domain (NTD) and (ii) C-terminal domain (CTD) with a single carotenoid as a chromophore spanning symmetrically in both domains. Blue-green or strong white light induces conversion of OCP from an inactive orange state (OCPO) to active red state (OCPR). Active form of OCP (OCPR) binds to core of light harvesting antenna complex, phycobilisome (PBS), where it quenches fluorescence and assists in dissipation of excess energy by non-radiative pathway. Prior to prevent wasteful quenching of fluorescence under light starvation, another protein named fluorescence recovery protein (FRP) partakes in decoupling OCPR from PBS and accelerates conversion of OCPR state back to OCPO state.

Shade lichens are characterized by rapid relaxation of non-photochemical quenching on transition to darkness

2021 ◽  
Vol 53 (5) ◽  
pp. 409-414
Author(s):  
Richard P. Beckett ◽  
Farida V. Minibayeva ◽  
Kwanele W. G. Mkhize
Keyword(s):  
Chlorophyll Fluorescence ◽  
Quantum Yield ◽  
Light Energy ◽  
Photochemical Quenching ◽  
Photosynthetic Organisms ◽  
Light Levels ◽  
Lower Light ◽  
Optimal Productivity ◽  
Sun And Shade ◽  
Non Photochemical Quenching

AbstractNon-photochemical quenching (NPQ) plays an important role in protecting photosynthetic organisms from photoinhibition by dissipating excess light energy as heat. However, excess NPQ can greatly reduce the quantum yield of photosynthesis at lower light levels. Recently, there has been considerable interest in understanding how plants balance NPQ to ensure optimal productivity in environments in which light levels are rapidly changing. In the present study, chlorophyll fluorescence was used to study the induction and relaxation of non-photochemical quenching (NPQ) in the dark and the induction of photosynthesis in ten species of lichens, five sampled from exposed and five sampled from shaded habitats. Here we show that the main difference between sun and shade lichens is the rate at which NPQ relaxes in the dark, rather than the speed that photosynthesis starts upon illumination. During the first two minutes in the dark, NPQ values in the five sun species declined only by an average of 2%, while by contrast, in shade species the average decline was 40%. For lichens growing in microhabitats where light levels are rapidly changing, rapid relaxation of NPQ may enable their photobionts to use the available light most efficiently.

scholarly journals The role of LHCBM1 in non-photochemical quenching in Chlamydomonas reinhardtii

2022 ◽  
Author(s):  
Xin Liu ◽  
Wojciech J Nawrocki ◽  
Roberta Croce
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Protein Complexes ◽  
Ph Sensor ◽  
High Light ◽  
Photochemical Quenching ◽  
Knock Out ◽  
Photosynthetic Organisms ◽  
Pigment Protein Complexes ◽  
Non Photochemical Quenching

Non-photochemical quenching (NPQ) is the process that protects photosynthetic organisms from photodamage by dissipating the energy absorbed in excess as heat. In the model green alga Chlamydomonas reinhardtii, NPQ was abolished in the knock-out mutants of the pigment-protein complexes LHCSR3 and LHCBM1. However, while LHCSR3 was shown to be a pH sensor and switching to a quenched conformation at low pH, the role of LHCBM1 in NPQ has not been elucidated yet. In this work, we combine biochemical and physiological measurements to study short-term high light acclimation of npq5, the mutant lacking LHCBM1. We show that while in low light in the absence of this complex, the antenna size of PSII is smaller than in its presence, this effect is marginal in high light, implying that a reduction of the antenna is not responsible for the low NPQ. We also show that the mutant expresses LHCSR3 at the WT level in high light, indicating that the absence of this complex is also not the reason. Finally, NPQ remains low in the mutant even when the pH is artificially lowered to values that can switch LHCSR3 to the quenched conformation. It is concluded that both LHCSR3 and LHCBM1 need to be present for the induction of NPQ and that LHCBM1 is the interacting partner of LHCSR3. This interaction can either enhance the quenching capacity of LHCSR3 or connect this complex with the PSII supercomplex.

scholarly journals Structural basis for the absence of low-energy chlorophylls responsible for photoprotection from a primitive cyanobacterial PSI

2021 ◽  
Author(s):  
Koji Kato ◽  
Tasuku Hamaguchi ◽  
Ryo Nagao ◽  
Keisuke Kawakami ◽  
Yoshifumi Ueno ◽  
...  
Keyword(s):  
Co2 Fixation ◽  
Energy Levels ◽  
Low Energy ◽  
Structural Basis ◽  
Photosynthetic Organisms ◽  
Cryo Electron Microscopy ◽  
Evolutionary Changes ◽  
Eukaryotic Organisms ◽  
Pigment Protein Complex ◽  
Resolution Structure

Photosystem I (PSI) of photosynthetic organisms is a multi-subunit pigment-protein complex and functions in light harvesting and photochemical charge-separation reactions, followed by reduction of NADP to NADPH required for CO2 fixation. PSI from different photosynthetic organisms has a variety of chlorophylls (Chls), some of which are at lower-energy levels than its reaction center P700, a special pair of Chls, and are called low-energy Chls. However, the site of low-energy Chls is still under debate. Here, we solved a 2.04-Å resolution structure of a PSI trimer by cryo-electron microscopy from a primitive cyanobacterium Gloeobacter violaceus PCC 7421, which has no low-energy Chls. The structure showed absence of some subunits commonly found in other cyanobacteria, confirming the primitive nature of this cyanobacterium. Comparison with the known structures of PSI from other cyanobacteria and eukaryotic organisms reveals that one dimeric and one trimeric Chls are lacking in the Gloeobacter PSI. The dimeric and trimeric Chls are named Low1 and Low2, respectively. Low2 does not exist in some cyanobacterial and eukaryotic PSIs, whereas Low1 is absent only in Gloeobacter. Since Gloeobacter is susceptible to light, this indicates that Low1 serves as a main photoprotection site in most oxyphototrophs, whereas Low2 is involved in either energy transfer or energy quenching in some of the oxyphototrophs. Thus, these findings provide insights into not only the functional significance of low-energy Chls in PSI, but also the evolutionary changes of low-energy Chls responsible for the photoprotection machinery from photosynthetic prokaryotes to eukaryotes.

scholarly journals DAY-LENGTH-DEPENDENT DELAYED-GREENING1, the Arabidopsis Homolog of the Cyanobacterial H+-Extrusion Protein, Is Essential for Chloroplast pH Regulation and Optimization of Non-Photochemical Quenching

2019 ◽  
Vol 60 (12) ◽  
pp. 2660-2671 ◽  
Author(s):  
Kyohei Harada ◽  
Takatoshi Arizono ◽  
Ryoichi Sato ◽  
Mai Duy Luu Trinh ◽  
Akira Hashimoto ◽  
...  
Keyword(s):  
Ph Regulation ◽  
Regulatory Protein ◽  
Protein A ◽  
Continuous Light ◽  
Membrane Vesicles ◽  
Light Energy ◽  
Day Length ◽  
Chloroplast Envelope ◽  
Photochemical Quenching ◽  
Non Photochemical Quenching

Abstract Plants convert solar energy into chemical energy through photosynthesis, which supports almost all life activities on earth. Because the intensity and quality of sunlight can change dramatically throughout the day, various regulatory mechanisms help plants adjust their photosynthetic output accordingly, including the regulation of light energy accumulation to prevent the generation of damaging reactive oxygen species. Non-photochemical quenching (NPQ) is a regulatory mechanism that dissipates excess light energy, but how it is regulated is not fully elucidated. In this study, we report a new NPQ-regulatory protein named Day-Length-dependent Delayed-Greening1 (DLDG1). The Arabidopsis DLDG1 associates with the chloroplast envelope membrane, and the dldg1 mutant had a large NPQ value compared with wild type. The mutant also had a pale-green phenotype in developing leaves but only under continuous light; this phenotype was not observed when dldg1 was cultured in the dark for ≥8 h/d. DLDG1 is a homolog of the plasma membrane-localizing cyanobacterial proton-extrusion-protein A that is required for light-induced H+ extrusion and also shows similarity in its amino-acid sequence to that of Ycf10 encoded in the plastid genome. Arabidopsis DLDG1 enhances the growth-retardation phenotype of the Escherichia coli K+/H+ antiporter mutant, and the everted membrane vesicles of the E. coli expressing DLDG1 show the K+/H+ antiport activity. Our findings suggest that DLDG1 functionally interacts with Ycf10 to control H+ homeostasis in chloroplasts, which is important for the light-acclimation response, by optimizing the extent of NPQ.

scholarly journals Non-Photochemical Quenching. A Response to Excess Light Energy

2001 ◽  
Vol 125 (4) ◽  
pp. 1558-1566 ◽  
Author(s):  
Patricia Müller ◽  
Xiao-Ping Li ◽  
Krishna K. Niyogi
Keyword(s):  
Light Energy ◽  
Photochemical Quenching ◽  
Excess Light ◽  
Non Photochemical Quenching

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 Transcriptional regulation of photoprotection in dark-to-light transition - more than just a matter of excess light energy

2021 ◽  
Author(s):  
Petra Redekop ◽  
Emanuel Sanz-Luque ◽  
Yizhong Yuan ◽  
Gaelle Villain ◽  
Dimitris Petroutsos ◽  
...  
Keyword(s):  
Light Intensity ◽  
Photosynthetic Electron Transport ◽  
Time Of Day ◽  
Photochemical Quenching ◽  
Mrna Accumulation ◽  
Photosynthetic Organisms ◽  
Light Spectra ◽  
Excess Light ◽  
Non Photochemical Quenching ◽  
The Impact

In nature, photosynthetic organisms are exposed to different light spectra and intensities depending on the time of day and atmospheric and environmental conditions. When photosynthetic cells absorb excess light, they induce non-photochemical quenching to avoid photo-damage and trigger expression of photoprotective genes. In this work, we used the green alga Chlamydomonas reinhardtii to assess the impact of light intensity, light quality, wavelength, photosynthetic electron transport and CO2 on induction of the photoprotective genes (LHCSR1, LHCSR3 and PSBS) during dark-to-light transitions. Induction (mRNA accumulation) occurred at very low light intensity, was independently modulated by blue and UV-B radiation through specific photoreceptors, and only LHCSR3 was strongly controlled by CO2 levels through a putative enhancer function of CIA5, a transcription factor that controls genes of the carbon concentrating mechanism. We propose a model that integrates inputs of independent signaling pathways and how they may help the cells anticipate diel conditions and survive in a dynamic light environment.

scholarly journals Light potentials of photosynthetic energy storage in the field: what limits the ability to use or dissipate rapidly increased light energy?

2021 ◽  
Vol 8 (12) ◽  
Author(s):  
Atsuko Kanazawa ◽  
Abhijnan Chattopadhyay ◽  
Sebastian Kuhlgert ◽  
Hainite Tuitupou ◽  
Tapabrata Maiti ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Electron Flow ◽  
Crop Productivity ◽  
Open Science ◽  
High Light ◽  
Light Energy ◽  
Photochemical Quenching ◽  
Plant Photosynthesis ◽  
Photosynthetic Control ◽  
Non Photochemical Quenching

The responses of plant photosynthesis to rapid fluctuations in environmental conditions are critical for efficient conversion of light energy. These responses are not well-seen laboratory conditions and are difficult to probe in field environments. We demonstrate an open science approach to this problem that combines multifaceted measurements of photosynthesis and environmental conditions, and an unsupervised statistical clustering approach. In a selected set of data on mint ( Mentha sp.), we show that ‘light potentials’ for linear electron flow and non-photochemical quenching (NPQ) upon rapid light increases are strongly suppressed in leaves previously exposed to low ambient photosynthetically active radiation (PAR) or low leaf temperatures, factors that can act both independently and cooperatively. Further analyses allowed us to test specific mechanisms. With decreasing leaf temperature or PAR, limitations to photosynthesis during high light fluctuations shifted from rapidly induced NPQ to photosynthetic control of electron flow at the cytochrome b 6 f complex. At low temperatures, high light induced lumen acidification, but did not induce NPQ, leading to accumulation of reduced electron transfer intermediates, probably inducing photodamage, revealing a potential target for improving the efficiency and robustness of photosynthesis. We discuss the implications of the approach for open science efforts to understand and improve crop productivity.

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