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Moore V, Vermaas W. Functional consequences of modification of the photosystem I/photosystem II ratio in the cyanobacterium Synechocystis sp. PCC 6803. J Bacteriol 2024; 206:e0045423. [PMID: 38695523 PMCID: PMC11112997 DOI: 10.1128/jb.00454-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Accepted: 03/16/2024] [Indexed: 05/24/2024] Open
Abstract
The stoichiometry of photosystem II (PSII) and photosystem I (PSI) varies between photoautotrophic organisms. The cyanobacterium Synechocystis sp. PCC 6803 maintains two- to fivefold more PSI than PSII reaction center complexes, and we sought to modify this stoichiometry by changing the promoter region of the psaAB operon. We thus generated mutants with varied psaAB expression, ranging from ~3% to almost 200% of the wild-type transcript level, but all showing a reduction in PSI levels, relative to wild type, suggesting a role of the psaAB promoter region in translational regulation. Mutants with 25%-70% of wild-type PSI levels were photoautotrophic, with whole-chain oxygen evolution rates on a per-cell basis comparable to that of wild type. In contrast, mutant strains with <10% of the wild-type level of PSI were obligate photoheterotrophs. Variable fluorescence yields of all mutants were much higher than those of wild type, indicating that the PSI content is localized differently than in wild type, with less transfer of PSII-absorbed energy to PSI. Strains with less PSI saturate at a higher light intensity, enhancing productivity at higher light intensities. This is similar to what is found in mutants with reduced antennae. With 3-(3,4-dichlorophenyl)-1,1-dimethylurea present, P700+ re-reduction kinetics in the mutants were slower than in wild type, consistent with the notion that there is less cyclic electron transport if less PSI is present. Overall, strains with a reduction in PSI content displayed surprisingly vigorous growth and linear electron transport. IMPORTANCE Consequences of reduction in photosystem I content were investigated in the cyanobacterium Synechocystis sp. PCC 6803 where photosystem I far exceeds the number of photosystem II complexes. Strains with less photosystem I displayed less cyclic electron transport, grew more slowly at lower light intensity and needed more light for saturation but were surprisingly normal in their whole-chain electron transport rates, implying that a significant fraction of photosystem I is dispensable for linear electron transport in cyanobacteria. These strains with reduced photosystem I levels may have biotechnological relevance as they grow well at higher light intensities.
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Affiliation(s)
- Vicki Moore
- School of Life Sciences and Center for Bioenergy and Photosynthesis, Arizona State University, Tempe, Arizona, USA
| | - Wim Vermaas
- School of Life Sciences and Center for Bioenergy and Photosynthesis, Arizona State University, Tempe, Arizona, USA
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Akhtar P, Balog-Vig F, Han W, Li X, Han G, Shen JR, Lambrev PH. Quantifying the Energy Spillover between Photosystems II and I in Cyanobacterial Thylakoid Membranes and Cells. PLANT & CELL PHYSIOLOGY 2024; 65:95-106. [PMID: 37874689 DOI: 10.1093/pcp/pcad127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 10/09/2023] [Accepted: 10/14/2023] [Indexed: 10/26/2023]
Abstract
The spatial separation of photosystems I and II (PSI and PSII) is thought to be essential for efficient photosynthesis by maintaining a balanced flow of excitation energy between them. Unlike the thylakoid membranes of plant chloroplasts, cyanobacterial thylakoids do not form tightly appressed grana stacks that enforce strict lateral separation. The coexistence of the two photosystems provides a ground for spillover-excitation energy transfer from PSII to PSI. Spillover has been considered as a pathway of energy transfer from the phycobilisomes to PSI and may also play a role in state transitions as means to avoid overexcitation of PSII. Here, we demonstrate a significant degree of energy spillover from PSII to PSI in reconstituted membranes and isolated thylakoid membranes of Thermosynechococcus (Thermostichus) vulcanus and Synechocystis sp. PCC 6803 by steady-state and time-resolved fluorescence spectroscopy. The quantum yield of spillover in these systems was determined to be up to 40%. Spillover was also found in intact cells but to a considerably lower degree (20%) than in isolated thylakoid membranes. The findings support a model of coexistence of laterally separated microdomains of PSI and PSII in the cyanobacterial cells as well as domains where the two photosystems are energetically connected. The methodology presented here can be applied to probe spillover in other photosynthetic organisms.
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Affiliation(s)
- Parveen Akhtar
- Institute of Plant Biology, HUN-REN Biological Research Centre, Szeged, Temesvári krt. 62, Szeged 6726, Hungary
| | - Fanny Balog-Vig
- Institute of Plant Biology, HUN-REN Biological Research Centre, Szeged, Temesvári krt. 62, Szeged 6726, Hungary
| | - Wenhui Han
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Xingyue Li
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Guangye Han
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Jian-Ren Shen
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- Research Institute for Interdisciplinary Science, Okayama University, Okayama, 700-8530 Japan
| | - Petar H Lambrev
- Institute of Plant Biology, HUN-REN Biological Research Centre, Szeged, Temesvári krt. 62, Szeged 6726, Hungary
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Canonico M, Konert G, Crepin A, Šedivá B, Kaňa R. Gradual Response of Cyanobacterial Thylakoids to Acute High-Light Stress-Importance of Carotenoid Accumulation. Cells 2021; 10:cells10081916. [PMID: 34440685 PMCID: PMC8393233 DOI: 10.3390/cells10081916] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 07/15/2021] [Accepted: 07/25/2021] [Indexed: 02/02/2023] Open
Abstract
Light plays an essential role in photosynthesis; however, its excess can cause damage to cellular components. Photosynthetic organisms thus developed a set of photoprotective mechanisms (e.g., non-photochemical quenching, photoinhibition) that can be studied by a classic biochemical and biophysical methods in cell suspension. Here, we combined these bulk methods with single-cell identification of microdomains in thylakoid membrane during high-light (HL) stress. We used Synechocystis sp. PCC 6803 cells with YFP tagged photosystem I. The single-cell data pointed to a three-phase response of cells to acute HL stress. We defined: (1) fast response phase (0–30 min), (2) intermediate phase (30–120 min), and (3) slow acclimation phase (120–360 min). During the first phase, cyanobacterial cells activated photoprotective mechanisms such as photoinhibition and non-photochemical quenching. Later on (during the second phase), we temporarily observed functional decoupling of phycobilisomes and sustained monomerization of photosystem II dimer. Simultaneously, cells also initiated accumulation of carotenoids, especially ɣ–carotene, the main precursor of all carotenoids. In the last phase, in addition to ɣ-carotene, we also observed accumulation of myxoxanthophyll and more even spatial distribution of photosystems and phycobilisomes between microdomains. We suggest that the overall carotenoid increase during HL stress could be involved either in the direct photoprotection (e.g., in ROS scavenging) and/or could play an additional role in maintaining optimal distribution of photosystems in thylakoid membrane to attain efficient photoprotection.
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Affiliation(s)
- Myriam Canonico
- Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Opatovický Mlýn, 379 81 Třeboň, Czech Republic; (M.C.); (G.K.); (A.C.); (B.Š.)
- Faculty of Science, University of South Bohemia in České Budějovice, Branišovská 31a, 370 05 České Budějovice, Czech Republic
| | - Grzegorz Konert
- Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Opatovický Mlýn, 379 81 Třeboň, Czech Republic; (M.C.); (G.K.); (A.C.); (B.Š.)
| | - Aurélie Crepin
- Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Opatovický Mlýn, 379 81 Třeboň, Czech Republic; (M.C.); (G.K.); (A.C.); (B.Š.)
| | - Barbora Šedivá
- Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Opatovický Mlýn, 379 81 Třeboň, Czech Republic; (M.C.); (G.K.); (A.C.); (B.Š.)
| | - Radek Kaňa
- Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Opatovický Mlýn, 379 81 Třeboň, Czech Republic; (M.C.); (G.K.); (A.C.); (B.Š.)
- Faculty of Science, University of South Bohemia in České Budějovice, Branišovská 31a, 370 05 České Budějovice, Czech Republic
- Correspondence:
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Bhatti AF, Kirilovsky D, van Amerongen H, Wientjes E. State transitions and photosystems spatially resolved in individual cells of the cyanobacterium Synechococcus elongatus. PLANT PHYSIOLOGY 2021; 186:569-580. [PMID: 33576804 PMCID: PMC8154081 DOI: 10.1093/plphys/kiab063] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 01/21/2021] [Indexed: 05/28/2023]
Abstract
State transitions are a low-light acclimation response through which the excitation of Photosystem I (PSI) and Photosystem II (PSII) is balanced; however, our understanding of this process in cyanobacteria remains poor. Here, picosecond fluorescence kinetics was recorded for the cyanobacterium Synechococcus elongatus using fluorescence lifetime imaging microscopy (FLIM), both upon chlorophyll a and phycobilisome (PBS) excitation. Fluorescence kinetics of single cells obtained using FLIM were compared with those of ensembles of cells obtained with time-resolved fluorescence spectroscopy. The global distribution of PSI and PSII and PBSs was mapped making use of their fluorescence kinetics. Both radial and lateral heterogeneity were found in the distribution of the photosystems. State transitions were studied at the level of single cells. FLIM results show that PSII quenching occurs in all cells, irrespective of their state (I or II). In S. elongatus cells, this quenching is enhanced in State II. Furthermore, the decrease of PSII fluorescence in State II was homogeneous throughout the cells, despite the inhomogeneous PSI/PSII ratio. Finally, some disconnected PBSs were resolved in most State II cells. Taken together our data show that PSI is enriched in the inner thylakoid, while state transitions occur homogeneously throughout the cell.
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Affiliation(s)
- Ahmad Farhan Bhatti
- Laboratory of Biophysics, Wageningen University, Wageningen, The Netherlands
| | - Diana Kirilovsky
- Institute for Integrative Biology of the Cell (12BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
| | - Herbert van Amerongen
- Laboratory of Biophysics, Wageningen University, Wageningen, The Netherlands
- MicroSpectroscopy Research Facility, Wageningen University, Wageningen, The Netherlands
| | - Emilie Wientjes
- Laboratory of Biophysics, Wageningen University, Wageningen, The Netherlands
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Kaňa R, Steinbach G, Sobotka R, Vámosi G, Komenda J. Fast Diffusion of the Unassembled PetC1-GFP Protein in the Cyanobacterial Thylakoid Membrane. Life (Basel) 2020; 11:life11010015. [PMID: 33383642 PMCID: PMC7823997 DOI: 10.3390/life11010015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 12/17/2020] [Accepted: 12/20/2020] [Indexed: 01/08/2023] Open
Abstract
Biological membranes were originally described as a fluid mosaic with uniform distribution of proteins and lipids. Later, heterogeneous membrane areas were found in many membrane systems including cyanobacterial thylakoids. In fact, cyanobacterial pigment-protein complexes (photosystems, phycobilisomes) form a heterogeneous mosaic of thylakoid membrane microdomains (MDs) restricting protein mobility. The trafficking of membrane proteins is one of the key factors for long-term survival under stress conditions, for instance during exposure to photoinhibitory light conditions. However, the mobility of unbound 'free' proteins in thylakoid membrane is poorly characterized. In this work, we assessed the maximal diffusional ability of a small, unbound thylakoid membrane protein by semi-single molecule FCS (fluorescence correlation spectroscopy) method in the cyanobacterium Synechocystis sp. PCC6803. We utilized a GFP-tagged variant of the cytochrome b6f subunit PetC1 (PetC1-GFP), which was not assembled in the b6f complex due to the presence of the tag. Subsequent FCS measurements have identified a very fast diffusion of the PetC1-GFP protein in the thylakoid membrane (D = 0.14 - 2.95 µm2s-1). This means that the mobility of PetC1-GFP was comparable with that of free lipids and was 50-500 times higher in comparison to the mobility of proteins (e.g., IsiA, LHCII-light-harvesting complexes of PSII) naturally associated with larger thylakoid membrane complexes like photosystems. Our results thus demonstrate the ability of free thylakoid-membrane proteins to move very fast, revealing the crucial role of protein-protein interactions in the mobility restrictions for large thylakoid protein complexes.
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Affiliation(s)
- Radek Kaňa
- Center ALGATECH, Institute of Microbiology of the Czech Academy of Sciences, 37901 Třeboň, Czech Republic; (R.S.); (J.K.)
- Correspondence:
| | - Gábor Steinbach
- Institute of Biophysics, Biological Research Center, 6726 Szeged, Hungary;
| | - Roman Sobotka
- Center ALGATECH, Institute of Microbiology of the Czech Academy of Sciences, 37901 Třeboň, Czech Republic; (R.S.); (J.K.)
| | - György Vámosi
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary;
| | - Josef Komenda
- Center ALGATECH, Institute of Microbiology of the Czech Academy of Sciences, 37901 Třeboň, Czech Republic; (R.S.); (J.K.)
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Canonico M, Konert G, Kaňa R. Plasticity of Cyanobacterial Thylakoid Microdomains Under Variable Light Conditions. FRONTIERS IN PLANT SCIENCE 2020; 11:586543. [PMID: 33304364 PMCID: PMC7693714 DOI: 10.3389/fpls.2020.586543] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 10/09/2020] [Indexed: 05/02/2023]
Abstract
Photosynthetic light reactions proceed in thylakoid membranes (TMs) due to the activity of pigment-protein complexes. These complexes are heterogeneously organized into granal/stromal thylakoids (in plants) or into recently identified cyanobacterial microdomains (MDs). MDs are characterized by specific ratios of photosystem I (PSI), photosystem II (PSII), and phycobilisomes (PBS) and they are visible as sub-micrometer sized areas with different fluorescence ratios. In this report, the process of long-term plasticity in cyanobacterial thylakoid MDs has been explored under variable growth light conditions using Synechocystis sp. PCC6803 expressing YFP tagged PSI. TM organization into MDs has been observed for all categorized shapes of cells independently of their stage in cell cycle. The heterogeneous PSI, PSII, and PBS thylakoid areas were also identified under two types of growth conditions: at continuous light (CL) and at light-dark (L-D) cycle. The acclimation from CL to L-D cycle changed spatial distribution of photosystems, in particular PSI became more evenly distributed in thylakoids under L-D cycle. The process of the spatial PSI (and partially also PSII) redistribution required 1 week and was accompanied by temporal appearance of PBS decoupling probably caused by the re-organization of photosystems. The overall acclimation we observed was defined as TM plasticity as it resembles higher plants grana/stroma reorganization at variable growth light conditions. In addition, we observed large cell to cell variability in the actual MDs organization. It leads us to suggest that the plasticity, and cell to cell variability in MDs could be a manifestation of phenotypic heterogeneity, a recently broadly discussed phenomenon for prokaryotes.
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Affiliation(s)
- Myriam Canonico
- Institute of Microbiology, CAS, Centrum Algatech, Třeboň, Czechia
- Faculty of Science, University of South Bohemia, České Budějovice, Czechia
| | - Grzegorz Konert
- Institute of Microbiology, CAS, Centrum Algatech, Třeboň, Czechia
| | - Radek Kaňa
- Institute of Microbiology, CAS, Centrum Algatech, Třeboň, Czechia
- Faculty of Science, University of South Bohemia, České Budějovice, Czechia
- *Correspondence: Radek Kaňa, ; orcid.org/0000-0001-5768-6902
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Strašková A, Steinbach G, Konert G, Kotabová E, Komenda J, Tichý M, Kaňa R. Pigment-protein complexes are organized into stable microdomains in cyanobacterial thylakoids. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2019; 1860:148053. [PMID: 31344362 DOI: 10.1016/j.bbabio.2019.07.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 06/28/2019] [Accepted: 07/18/2019] [Indexed: 02/03/2023]
Abstract
Thylakoids are the place of the light-photosynthetic reactions. To gain maximal efficiency, these reactions are conditional to proper pigment-pigment and protein-protein interactions. In higher plants thylakoids, the interactions lead to a lateral asymmetry in localization of protein complexes (i.e. granal/stromal thylakoids) that have been defined as a domain-like structures characteristic by different biochemical composition and function (Albertsson P-Å. 2001,Trends Plant Science 6: 349-354). We explored this complex organization of thylakoid pigment-proteins at single cell level in the cyanobacterium Synechocystis sp. PCC 6803. Our 3D confocal images captured heterogeneous distribution of all main photosynthetic pigment-protein complexes (PPCs), Photosystem I (fluorescently tagged by YFP), Photosystem II and Phycobilisomes. The acquired images depicted cyanobacterial thylakoid membrane as a stable, mosaic-like structure formed by microdomains (MDs). These microcompartments are of sub-micrometer in sizes (~0.5-1.5 μm), typical by particular PPCs ratios and importantly without full segregation of observed complexes. The most prevailing MD is represented by MD with high Photosystem I content which allows also partial separation of Photosystems like in higher plants thylakoids. We assume that MDs stability (in minutes) provides optimal conditions for efficient excitation/electron transfer. The cyanobacterial MDs thus define thylakoid membrane organization as a system controlled by co-localization of three main PPCs leading to formation of thylakoid membrane mosaic. This organization might represent evolutional and functional precursor for the granal/stromal spatial heterogeneity in photosystems that is typical for higher plant thylakoids.
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Affiliation(s)
- A Strašková
- Institute of Microbiology, Czech Academy of Sciences, Centre Algatech, Novohradská 237, 379 81 Třeboň, Czech Republic
| | - G Steinbach
- Institute of Microbiology, Czech Academy of Sciences, Centre Algatech, Novohradská 237, 379 81 Třeboň, Czech Republic
| | - G Konert
- Institute of Microbiology, Czech Academy of Sciences, Centre Algatech, Novohradská 237, 379 81 Třeboň, Czech Republic
| | - E Kotabová
- Institute of Microbiology, Czech Academy of Sciences, Centre Algatech, Novohradská 237, 379 81 Třeboň, Czech Republic
| | - J Komenda
- Institute of Microbiology, Czech Academy of Sciences, Centre Algatech, Novohradská 237, 379 81 Třeboň, Czech Republic
| | - M Tichý
- Institute of Microbiology, Czech Academy of Sciences, Centre Algatech, Novohradská 237, 379 81 Třeboň, Czech Republic
| | - R Kaňa
- Institute of Microbiology, Czech Academy of Sciences, Centre Algatech, Novohradská 237, 379 81 Třeboň, Czech Republic.
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