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Mallén-Ponce MJ, Huertas MJ, Sánchez-Riego AM, Florencio FJ. Depletion of m-type thioredoxin impairs photosynthesis, carbon fixation, and oxidative stress in cyanobacteria. PLANT PHYSIOLOGY 2021; 187:1325-1340. [PMID: 34618018 PMCID: PMC8566235 DOI: 10.1093/plphys/kiab321] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 06/21/2021] [Indexed: 06/13/2023]
Abstract
Thioredoxins (Trxs) are disulfide oxidoreductases that regulate many biological processes. The m-type thioredoxin (TrxA) is the only Trx present in all oxygenic photosynthetic organisms. Extensive biochemical and proteomic analyses have identified many TrxA target proteins in different photosynthetic organisms. However, the precise function of this essential protein in vivo is still poorly known. In this study, we generated a conditional Synechocystis sp. PCC 6803 mutant strain (STXA2) using an on-off promoter that is able to survive with only 2% of the TrxA level of the wild-type (WT) strain. STXA2 characterization revealed that TrxA depletion results in growth arrest and pronounced impairment of photosynthesis and the Calvin-Benson-Bassham (CBB) cycle. Analysis of the in vivo redox state of the bifunctional enzyme fructose-1,6-bisphosphatase/sedoheptulose-1,7-bisphosphatase showed higher levels of oxidation that affected enzyme activity in STXA2. This result implies that TrxA-mediated redox regulation of the CBB cycle is conserved in both cyanobacteria and chloroplasts, although the targets have different evolutionary origins. The STXA2 strain also accumulated more reactive oxygen species and was more sensitive to oxidative stress than the WT. Analysis of the in vivo redox state of 2-Cys peroxiredoxin revealed full oxidation, corresponding with TrxA depletion. Overall, these results indicate that depletion of TrxA in STXA2 greatly alters the cellular redox state, interfering with essential processes such as photosynthetic machinery operativity, carbon assimilation, and oxidative stress response. The TrxA regulatory role appears to be conserved along the evolution of oxygenic photosynthetic organisms.
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Affiliation(s)
- Manuel J Mallén-Ponce
- Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla-CSIC, Américo Vespucio 49, 41092 Sevilla, Spain
| | - María José Huertas
- Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla-CSIC, Américo Vespucio 49, 41092 Sevilla, Spain
| | - Ana María Sánchez-Riego
- Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla-CSIC, Américo Vespucio 49, 41092 Sevilla, Spain
| | - Francisco J Florencio
- Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla-CSIC, Américo Vespucio 49, 41092 Sevilla, Spain
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Patil PP, Vass I, Kodru S, Szabó M. A multi-parametric screening platform for photosynthetic trait characterization of microalgae and cyanobacteria under inorganic carbon limitation. PLoS One 2020; 15:e0236188. [PMID: 32701995 PMCID: PMC7377499 DOI: 10.1371/journal.pone.0236188] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Accepted: 06/30/2020] [Indexed: 11/18/2022] Open
Abstract
Microalgae and cyanobacteria are considered as important model organisms to investigate the biology of photosynthesis; moreover, they are valuable sources of biomolecules for several biotechnological applications. Understanding the species-specific traits of photosynthetic electron transport is extremely important, because it contributes to the regulation of ATP/NADPH ratio, which has direct/indirect links to carbon fixation and other metabolic pathways and thus overall growth and biomass production. In the present work, a cuvette-based setup is developed, in which a combination of measurements of dissolved oxygen, pH, chlorophyll fluorescence and NADPH kinetics can be performed without disturbing the physiological status of the sample. The suitability of the system is demonstrated using a model cyanobacterium Synechocystis sp. PCC6803, as well as biofuel-candidate microalgae species, such as Chlorella sorokiniana, Dunaliella salina and Nannochloropsis limnetica undergoing inorganic carbon (Ci) limitation. Inorganic carbon limitation, induced by photosynthetic Ci uptake under continuous illumination, caused a decrease in the effective quantum yield of PSII (Y(II)) and loss of oxygen-evolving capacity in all species investigated here; these effects were largely recovered by the addition of NaHCO3. Detailed analysis of the dark-light and light-dark transitions of NADPH production/uptake and changes in chlorophyll fluorescence kinetics revealed species- and condition-specific responses. These responses indicate that the impact of decreased Calvin-Benson cycle activity on photosynthetic electron transport pathways involving several sections of the electron transport chain (such as electron transfer via the QA-QB-plastoquinone pool, the redox state of the plastoquinone pool) can be analyzed with high sensitivity in a comparative manner. Therefore, the integrated system presented here can be applied for screening for specific traits in several significant species at different stages of inorganic carbon limitation, a condition that strongly impacts primary productivity.
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Affiliation(s)
| | - Imre Vass
- Institute of Plant Biology, Biological Research Centre, Szeged, Hungary
| | - Sandeesha Kodru
- Institute of Plant Biology, Biological Research Centre, Szeged, Hungary
- Biology PhD School, Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Milán Szabó
- Institute of Plant Biology, Biological Research Centre, Szeged, Hungary
- Climate Change Cluster, University of Technology Sydney, Ultimo, Australia
- * E-mail:
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Zheng L, Li Y, Li X, Zhong Q, Li N, Zhang K, Zhang Y, Chu H, Ma C, Li G, Zhao J, Gao N. Structural and functional insights into the tetrameric photosystem I from heterocyst-forming cyanobacteria. NATURE PLANTS 2019; 5:1087-1097. [PMID: 31595062 DOI: 10.1038/s41477-019-0525-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Accepted: 09/05/2019] [Indexed: 05/05/2023]
Abstract
Two large protein-cofactor complexes, photosystem I and photosystem II, are the central components of photosynthesis in the thylakoid membranes. Here, we report the 2.37-Å structure of a tetrameric photosystem I complex from a heterocyst-forming cyanobacterium Anabaena sp. PCC 7120. Four photosystem I monomers, organized in a dimer of dimer, form two distinct interfaces that are largely mediated by specifically orientated polar lipids, such as sulfoquinovosyl diacylglycerol. The structure depicts a more closely connected network of chlorophylls across monomer interfaces than those seen in trimeric PSI from thermophilic cyanobacteria, possibly allowing a more efficient energy transfer between monomers. Our physiological data also revealed a functional link of photosystem I oligomerization to cyclic electron flow and thylakoid membrane organization.
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Affiliation(s)
- Lvqin Zheng
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, School of Life Sciences, Peking University, Beijing, China
| | - Yanbing Li
- State Key Laboratory of Protein and Plant Genetic Engineering, School of Life Sciences, Peking University, Beijing, China
| | - Xiying Li
- State Key Laboratory of Protein and Plant Genetic Engineering, School of Life Sciences, Peking University, Beijing, China
| | - Qinglu Zhong
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
| | - Ningning Li
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, School of Life Sciences, Peking University, Beijing, China
| | - Kun Zhang
- State Key Laboratory of Protein and Plant Genetic Engineering, School of Life Sciences, Peking University, Beijing, China
| | - Yuebin Zhang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
| | - Huiying Chu
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
| | - Chengying Ma
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, School of Life Sciences, Peking University, Beijing, China
| | - Guohui Li
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China.
| | - Jindong Zhao
- State Key Laboratory of Protein and Plant Genetic Engineering, School of Life Sciences, Peking University, Beijing, China.
- Chinese Academy of Sciences Key Laboratory of Phycological Research, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, China.
| | - Ning Gao
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, School of Life Sciences, Peking University, Beijing, China.
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