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 LHCSR1 induces a fast and reversible pH-dependent fluorescence quenching in LHCII in Chlamydomonas reinhardtii cells

2016 ◽  
Vol 113 (27) ◽  
pp. 7673-7678 ◽  
Author(s):  
Emine Dinc ◽  
Lijin Tian ◽  
Laura M. Roy ◽  
Robyn Roth ◽  
Ursula Goodenough ◽  
...  
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Light Harvesting ◽  
Ph Sensor ◽  
Complex Stress ◽  
Minimal Cell ◽  
Light Harvesting Complex ◽  
In Vivo Experiments ◽  
Ph Dependent

To avoid photodamage, photosynthetic organisms are able to thermally dissipate the energy absorbed in excess in a process known as nonphotochemical quenching (NPQ). Although NPQ has been studied extensively, the major players and the mechanism of quenching remain debated. This is a result of the difficulty in extracting molecular information from in vivo experiments and the absence of a validation system for in vitro experiments. Here, we have created a minimal cell of the green alga Chlamydomonas reinhardtii that is able to undergo NPQ. We show that LHCII, the main light harvesting complex of algae, cannot switch to a quenched conformation in response to pH changes by itself. Instead, a small amount of the protein LHCSR1 (light-harvesting complex stress related 1) is able to induce a large, fast, and reversible pH-dependent quenching in an LHCII-containing membrane. These results strongly suggest that LHCSR1 acts as pH sensor and that it modulates the excited state lifetimes of a large array of LHCII, also explaining the NPQ observed in the LHCSR3-less mutant. The possible quenching mechanisms are discussed.

scholarly journals Identification of distinct pH- and zeaxanthin-dependent quenching in LHCSR3 from Chlamydomonas reinhardtii

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Julianne M Troiano ◽  
Federico Perozeni ◽  
Raymundo Moya ◽  
Luca Zuliani ◽  
Kwangyrul Baek ◽  
...  
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Light Harvesting ◽  
Complex Stress ◽  
Oxygen Species ◽  
Absorbed Energy ◽  
Light Harvesting Complexes ◽  
Light Harvesting Complex ◽  
Photosynthetic Organisms

Under high light, oxygenic photosynthetic organisms avoid photodamage by thermally dissipating absorbed energy, which is called nonphotochemical quenching. In green algae, a chlorophyll and carotenoid-binding protein, light-harvesting complex stress-related (LHCSR3), detects excess energy via a pH drop and serves as a quenching site. Using a combined in vivo and in vitro approach, we investigated quenching within LHCSR3 from Chlamydomonas reinhardtii. In vitro two distinct quenching processes, individually controlled by pH and zeaxanthin, were identified within LHCSR3. The pH-dependent quenching was removed within a mutant LHCSR3 that lacks the residues that are protonated to sense the pH drop. Observation of quenching in zeaxanthin-enriched LHCSR3 even at neutral pH demonstrated zeaxanthin-dependent quenching, which also occurs in other light-harvesting complexes. Either pH- or zeaxanthin-dependent quenching prevented the formation of damaging reactive oxygen species, and thus the two quenching processes may together provide different induction and recovery kinetics for photoprotection in a changing environment.

scholarly journals Identification of parallel pH- and zeaxanthin-dependent quenching of excess energy in LHCSR3 in Chlamydomonas reinhardtii

2020 ◽  
Author(s):  
Julianne M. Troiano ◽  
Federico Perozeni ◽  
Raymundo Moya ◽  
Luca Zuliani ◽  
Kwangryul Baek ◽  
...  
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Light Harvesting ◽  
Complex Stress ◽  
Excess Energy ◽  
Photochemical Quenching ◽  
Light Harvesting Complexes ◽  
Light Harvesting Complex ◽  
Non Photochemical Quenching

AbstractUnder high light conditions, oxygenic photosynthetic organisms avoid photodamage by thermally dissipating excess absorbed energy, which is called non-photochemical quenching (NPQ). In green algae, a chlorophyll and carotenoid-binding protein, light-harvesting complex stress-related (LHCSR3), detects excess energy via pH and serves as a quenching site. However, the mechanisms by which LHCSR3 functions have not been determined. Using a combined in vivo and in vitro approach, we identify two parallel yet distinct quenching processes, individually controlled by pH and carotenoid composition, and their likely molecular origin within LHCSR3 from Chlamydomonas reinhardtii. The pH-controlled quenching is removed within a mutant LHCSR3 that lacks the protonable residues responsible for sensing pH. Constitutive quenching in zeaxanthin-enriched systems demonstrates zeaxanthin-controlled quenching, which may be shared with other light-harvesting complexes. We show that both quenching processes prevent the formation of damaging reactive oxygen species, and thus provide distinct timescales and mechanisms of protection in a changing environment.

scholarly journals LHCSR3 is a nonphotochemical quencher of both photosystems inChlamydomonas reinhardtii

2019 ◽  
Vol 116 (10) ◽  
pp. 4212-4217 ◽  
Author(s):  
Laura Girolomoni ◽  
Stefano Cazzaniga ◽  
Alberta Pinnola ◽  
Federico Perozeni ◽  
Matteo Ballottari ◽  
...  
Keyword(s):  
Light Harvesting ◽  
Internal Standard ◽  
Green Fluorescence Protein ◽  
Complex Stress ◽  
Antenna System ◽  
Thermal Dissipation ◽  
Light Harvesting Complexes ◽  
Light Harvesting Complex ◽  
Whole Cells ◽  
Photosynthetic Organisms

Photosynthetic organisms prevent oxidative stress from light energy absorbed in excess through several photoprotective mechanisms. A major component is thermal dissipation of chlorophyll singlet excited states and is called nonphotochemical quenching (NPQ). NPQ is catalyzed in green algae by protein subunits called LHCSRs (Light Harvesting Complex Stress Related), homologous to the Light Harvesting Complexes (LHC), constituting the antenna system of both photosystem I (PSI) and PSII. We investigated the role of LHCSR1 and LHCSR3 in NPQ activation to verify whether these proteins are involved in thermal dissipation of PSI excitation energy, in addition to their well-known effect on PSII. To this aim, we measured the fluorescence emitted at 77 K by whole cells in a quenched or unquenched state, using green fluorescence protein as the internal standard. We show that NPQ activation by high light treatment inChlamydomonas reinhardtiileads to energy quenching in both PSI and PSII antenna systems. By analyzing quenching properties of mutants affected on the expression of LHCSR1 or LHCSR3 gene products and/or state 1–state 2 transitions or zeaxanthin accumulation, namely,npq4,stt7,stt7 npq4,npq4 lhcsr1,lhcsr3-complementednpq4 lhcsr1andnpq1, we showed that PSI undergoes NPQ through quenching of the associated LHCII antenna. This quenching event is fast-reversible on switching the light off, is mainly related to LHCSR3 activity, and is dependent on thylakoid luminal pH. Moreover, PSI quenching could also be observed in the absence of zeaxanthin or STT7 kinase activity.

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 Zeaxanthin Binds to Light-Harvesting Complex Stress-Related Protein to Enhance Nonphotochemical Quenching in Physcomitrella patens

2013 ◽  
Vol 25 (9) ◽  
pp. 3519-3534 ◽  
Author(s):  
Alberta Pinnola ◽  
Luca Dall’Osto ◽  
Caterina Gerotto ◽  
Tomas Morosinotto ◽  
Roberto Bassi ◽  
...  
Keyword(s):  
Physcomitrella Patens ◽  
Light Harvesting ◽  
Complex Stress ◽  
Nonphotochemical Quenching ◽  
Related Protein ◽  
Light Harvesting Complex

The rise and fall of Light-Harvesting Complex Stress-Related proteins as photoprotection agents during evolution

2019 ◽  
Vol 70 (20) ◽  
pp. 5527-5535 ◽  
Author(s):  
Alberta Pinnola
Keyword(s):  
Vascular Plants ◽  
Light Harvesting ◽  
Complex Stress ◽  
Excess Energy ◽  
Light Harvesting Complex ◽  
Quenching Mechanisms ◽  
Related Proteins ◽  
Role Of Light ◽  
Psbs Protein

This review on the evolution of quenching mechanisms for excess energy dissipation focuses on the role of Light-Harvesting Complex Stress-Related (LHCSR) proteins versus Photosystem II Subunit S (PSBS) protein, and the reasons for the redundancy of LHCSR in vascular plants as PSBS became established.

The evolution of the photoprotective antenna proteins in oxygenic photosynthetic eukaryotes

2018 ◽  
Vol 46 (5) ◽  
pp. 1263-1277 ◽  
Author(s):  
Vasco Giovagnetti ◽  
Alexander V. Ruban
Keyword(s):  
Vascular Plants ◽  
Light Harvesting ◽  
Current Knowledge ◽  
Complex Stress ◽  
Photochemical Quenching ◽  
Light Harvesting Complex ◽  
Photosynthetic Organisms ◽  
Photosynthetic Eukaryotes ◽  
Non Photochemical Quenching ◽  
Energy Dependent

Photosynthetic organisms require rapid and reversible down-regulation of light harvesting to avoid photodamage. Response to unpredictable light fluctuations is achieved by inducing energy-dependent quenching, qE, which is the major component of the process known as non-photochemical quenching (NPQ) of chlorophyll fluorescence. qE is controlled by the operation of the xanthophyll cycle and accumulation of specific types of proteins, upon thylakoid lumen acidification. The protein cofactors so far identified to modulate qE in photosynthetic eukaryotes are the photosystem II subunit S (PsbS) and light-harvesting complex stress-related (LHCSR/LHCX) proteins. A transition from LHCSR- to PsbS-dependent qE took place during the evolution of the Viridiplantae (also known as ‘green lineage’ organisms), such as green algae, mosses and vascular plants. Multiple studies showed that LHCSR and PsbS proteins have distinct functions in the mechanism of qE. LHCX(-like) proteins are closely related to LHCSR proteins and found in ‘red lineage’ organisms that contain secondary red plastids, such as diatoms. Although LHCX proteins appear to control qE in diatoms, their role in the mechanism remains poorly understood. Here, we present the current knowledge on the functions and evolution of these crucial proteins, which evolved in photosynthetic eukaryotes to optimise light harvesting.

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