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.

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.

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.

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 Ascorbate deficiency does not limit non-photochemical quenching in Chlamydomonas reinhardtii

2019 ◽  
Author(s):  
André Vidal-Meireles ◽  
Dávid Tóth ◽  
László Kovács ◽  
Juliane Neupert ◽  
Szilvia Z. Tóth
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Vascular Plants ◽  
Regulation Of Gene Expression ◽  
Growth Conditions ◽  
Photochemical Quenching ◽  
Wild Type ◽  
Knockout Mutant ◽  
Dependent Component ◽  
Non Photochemical Quenching ◽  
Energy Dependent

SummaryAscorbate (vitamin C) plays essential roles in development, signaling, hormone biosynthesis, regulation of gene expression, stress resistance and photoprotection. In vascular plants, violaxanthin de-epoxidase (VDE) requires ascorbate (Asc) as reductant, thereby it is required for the energy-dependent component of non-photochemical quenching (NPQ). In order to assess the role of Asc in NPQ in green algae, which are known to contain low amounts of Asc, we searched for an insertional Chlamydomonas reinhardtii mutant affected in the VTC2 gene, essential for Asc biosynthesis. The Crvtc2-1 knockout mutant was viable and, depending on the growth conditions, it contained 10 to 20% Asc relative to its wild type. When Chlamydomonas was grown photomixotrophically at moderate light, the zeaxanthin-dependent component of NPQ emerged upon strong red illumination both in the Crvtc2-1 mutant and in its wild type. Deepoxidation was unaffected by Asc deficiency, demonstrating that the Chlorophycean VDE found in Chlamydomonas does not require Asc as a reductant. The rapidly induced, energy-dependent NPQ component, characteristic of photoautotrophic Chlamydomonas cultures grown at high light, was not limited by Asc deficiency either. On the other hand, a reactive oxygen species-induced photoinhibitory NPQ component was greatly enhanced upon Asc deficiency, both under photomixotrophic and photoautotrophic conditions. These results demonstrate that Asc has distinct roles in NPQ formation in Chlamydomonas than in vascular plants.One-sentence summaryIn Chlamydomonas -in contrast to seed plants-, ascorbate is not required for violaxanthin deepoxidation and energy-dependent non-photochemical quenching but it mitigates photoinhibitory quenching.

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.

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