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Torres-Romero I, Zhang H, Wijker RS, Clark AJ, McLeod RE, Jaggi M, Stoll HM. Hydrogen isotope fractionation is controlled by CO 2 in coccolithophore lipids. Proc Natl Acad Sci U S A 2024; 121:e2318570121. [PMID: 38905238 PMCID: PMC11214045 DOI: 10.1073/pnas.2318570121] [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: 10/26/2023] [Accepted: 05/21/2024] [Indexed: 06/23/2024] Open
Abstract
Hydrogen isotope ratios (δ2H) represent an important natural tracer of metabolic processes, but quantitative models of processes controlling H-fractionation in aquatic photosynthetic organisms are lacking. Here, we elucidate the underlying physiological controls of 2H/1H fractionation in algal lipids by systematically manipulating temperature, light, and CO2(aq) in continuous cultures of the haptophyte Gephyrocapsa oceanica. We analyze the hydrogen isotope fractionation in alkenones (αalkenone), a class of acyl lipids specific to this species and other haptophyte algae. We find a strong decrease in the αalkenone with increasing CO2(aq) and confirm αalkenone correlates with temperature and light. Based on the known biosynthesis pathways, we develop a cellular model of the δ2H of algal acyl lipids to evaluate processes contributing to these controls on fractionation. Simulations show that longer residence times of NADPH in the chloroplast favor a greater exchange of NADPH with 2H-richer intracellular water, increasing αalkenone. Higher chloroplast CO2(aq) and temperature shorten NADPH residence time by enhancing the carbon fixation and lipid synthesis rates. The inverse correlation of αalkenone to CO2(aq) in our cultures suggests that carbon concentrating mechanisms (CCM) do not achieve a constant saturation of CO2 at the Rubisco site, but rather that chloroplast CO2 varies with external CO2(aq). The pervasive inverse correlation of αalkenone with CO2(aq) in the modern and preindustrial ocean also suggests that natural populations may not attain a constant saturation of Rubisco with the CCM. Rather than reconstructing growth water, αalkenone may be a powerful tool to elucidate the carbon limitation of photosynthesis.
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Affiliation(s)
- Ismael Torres-Romero
- Climate Geology, Department of Earth Sciences, ETH Zürich, Zurich8092, Switzerland
| | - Hongrui Zhang
- Climate Geology, Department of Earth Sciences, ETH Zürich, Zurich8092, Switzerland
| | - Reto S. Wijker
- Climate Geology, Department of Earth Sciences, ETH Zürich, Zurich8092, Switzerland
| | - Alexander J. Clark
- Climate Geology, Department of Earth Sciences, ETH Zürich, Zurich8092, Switzerland
| | - Rachel E. McLeod
- Climate Geology, Department of Earth Sciences, ETH Zürich, Zurich8092, Switzerland
| | - Madalina Jaggi
- Climate Geology, Department of Earth Sciences, ETH Zürich, Zurich8092, Switzerland
| | - Heather M. Stoll
- Climate Geology, Department of Earth Sciences, ETH Zürich, Zurich8092, Switzerland
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2
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Mishra S, Sharma A, Srivastava AK. Ascorbic acid: a metabolite switch for designing stress-smart crops. Crit Rev Biotechnol 2024:1-17. [PMID: 38163756 DOI: 10.1080/07388551.2023.2286428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 11/02/2023] [Indexed: 01/03/2024]
Abstract
Plant growth and productivity are continually being challenged by a diverse array of abiotic stresses, including: water scarcity, extreme temperatures, heavy metal exposure, and soil salinity. A common theme in these stresses is the overproduction of reactive oxygen species (ROS), which disrupts cellular redox homeostasis causing oxidative damage. Ascorbic acid (AsA), commonly known as vitamin C, is an essential nutrient for humans, and also plays a crucial role in the plant kingdom. AsA is synthesized by plants through the d-mannose/l-galactose pathway that functions as a powerful antioxidant and protects plant cells from ROS generated during photosynthesis. AsA controls several key physiological processes, including: photosynthesis, respiration, and carbohydrate metabolism, either by acting as a co-factor for metabolic enzymes or by regulating cellular redox-status. AsA's multi-functionality uniquely positions it to integrate and recalibrate redox-responsive transcriptional/metabolic circuits and essential biological processes, in accordance to developmental and environmental cues. In recognition of this, we present a systematic overview of current evidence highlighting AsA as a central metabolite-switch in plants. Further, a comprehensive overview of genetic manipulation of genes involved in AsA metabolism has been provided along with the bottlenecks and future research directions, that could serve as a framework for designing "stress-smart" crops in future.
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Affiliation(s)
- Shefali Mishra
- Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Mumbai, India
| | - Ankush Sharma
- Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Mumbai, India
- Homi Bhabha National Institute, Mumbai, India
| | - Ashish Kumar Srivastava
- Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Mumbai, India
- Homi Bhabha National Institute, Mumbai, India
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3
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Ravanfar R, Sheng Y, Gray HB, Winkler JR. Tryptophan extends the life of cytochrome P450. Proc Natl Acad Sci U S A 2023; 120:e2317372120. [PMID: 38060561 PMCID: PMC10722969 DOI: 10.1073/pnas.2317372120] [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: 10/06/2023] [Accepted: 11/04/2023] [Indexed: 12/17/2023] Open
Abstract
Powerfully oxidizing enzymes need protective mechanisms to prevent self-destruction. The flavocytochrome P450 BM3 from Priestia megaterium (P450BM3) is a self-sufficient monooxygenase that hydroxylates fatty acid substrates using O2 and NADPH as co-substrates. Hydroxylation of long-chain fatty acids (≥C14) is well coupled to O2 and NADPH consumption, but shorter chains (≤C12) are more poorly coupled. Hydroxylation of p-nitrophenoxydodecanoic acid by P450BM3 produces a spectrophotometrically detectable product wherein the coupling of NADPH consumption to product formation is just 10%. Moreover, the rate of NADPH consumption is 1.8 times that of O2 consumption, indicating that an oxidase uncoupling pathway is operative. Measurements of the total number of enzyme turnovers before inactivation (TTN) indicate that higher NADPH concentrations increase TTN. At lower NADPH levels, added ascorbate increases TTN, while a W96H mutation leads to a decrease. The W96 residue is about 7 Å from the P450BM3 heme and serves as a gateway residue in a tryptophan/tyrosine (W/Y) hole transport chain from the heme to a surface tyrosine residue. The data indicate that two oxidase pathways protect the enzyme from damage by intercepting the powerfully oxidizing enzyme intermediate (Compound I) and returning it to its resting state. At high NADPH concentrations, reducing equivalents from the flavoprotein are delivered to Compound I by the usual reductase pathway. When NADPH is not abundant, however, oxidizing equivalents from Compound I can traverse a W/Y chain, arriving at the enzyme surface where they are scavenged by reductants. Ubiquitous tryptophan/tyrosine chains in highly oxidizing enzymes likely perform similar protective functions.
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Affiliation(s)
- Raheleh Ravanfar
- Beckman Institute, California Institute of Technology, Pasadena, CA91125
| | - Yuling Sheng
- Beckman Institute, California Institute of Technology, Pasadena, CA91125
| | - Harry B. Gray
- Beckman Institute, California Institute of Technology, Pasadena, CA91125
| | - Jay R. Winkler
- Beckman Institute, California Institute of Technology, Pasadena, CA91125
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4
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Tanaka K, Shirai T, Vavricka CJ, Matsuda M, Kondo A, Hasunuma T. Dark accumulation of downstream glycolytic intermediates initiates robust photosynthesis in cyanobacteria. PLANT PHYSIOLOGY 2023; 191:2400-2413. [PMID: 36574371 PMCID: PMC10069908 DOI: 10.1093/plphys/kiac602] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2022] [Accepted: 12/09/2022] [Indexed: 06/19/2023]
Abstract
Photosynthesis must maintain stability and robustness throughout fluctuating natural environments. In cyanobacteria, dark-to-light transition leads to drastic metabolic changes from dark respiratory metabolism to CO2 fixation through the Calvin-Benson-Bassham (CBB) cycle using energy and redox equivalents provided by photosynthetic electron transfer. Previous studies have shown that catabolic metabolism supports the smooth transition into CBB cycle metabolism. However, metabolic mechanisms for robust initiation of photosynthesis are poorly understood due to lack of dynamic metabolic characterizations of dark-to-light transitions. Here, we show rapid dynamic changes (on a time scale of seconds) in absolute metabolite concentrations and 13C tracer incorporation after strong or weak light irradiation in the cyanobacterium Synechocystis sp. PCC 6803. Integration of this data enabled estimation of time-resolved nonstationary metabolic flux underlying CBB cycle activation. This dynamic metabolic analysis indicated that downstream glycolytic intermediates, including phosphoglycerate and phosphoenolpyruvate, accumulate under dark conditions as major substrates for initial CO2 fixation. Compared with wild-type Synechocystis, significant decreases in the initial oxygen evolution rate were observed in 12 h dark preincubated mutants deficient in glycogen degradation or oxidative pentose phosphate pathways. Accordingly, the degree of decrease in the initial oxygen evolution rate was proportional to the accumulated pool size of glycolytic intermediates. These observations indicate that the accumulation of glycolytic intermediates is essential for efficient metabolism switching under fluctuating light environments.
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Affiliation(s)
- Kenya Tanaka
- Engineering Biology Research Center, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
- Graduate School of Science, Innovation and Technology, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
- Research Center for Solar Energy Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Tomokazu Shirai
- Graduate School of Science, Innovation and Technology, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
- RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro, Tsurumi, Yokohama, Kanagawa 230-0045, Japan
| | - Christopher J Vavricka
- Department of Biotechnology and Life Science, Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo, 184-8588, Japan
| | - Mami Matsuda
- Graduate School of Science, Innovation and Technology, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
| | - Akihiko Kondo
- Engineering Biology Research Center, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
- Graduate School of Science, Innovation and Technology, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
- RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro, Tsurumi, Yokohama, Kanagawa 230-0045, Japan
- Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
| | - Tomohisa Hasunuma
- Engineering Biology Research Center, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
- Graduate School of Science, Innovation and Technology, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
- RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro, Tsurumi, Yokohama, Kanagawa 230-0045, Japan
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5
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Barone GD, Hubáček M, Malihan-Yap L, Grimm HC, Nikkanen L, Pacheco CC, Tamagnini P, Allahverdiyeva Y, Kourist R. Towards the rate limit of heterologous biotechnological reactions in recombinant cyanobacteria. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2023; 16:4. [PMID: 36609316 PMCID: PMC9825001 DOI: 10.1186/s13068-022-02237-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 12/04/2022] [Indexed: 01/09/2023]
Abstract
BACKGROUND Cyanobacteria have emerged as highly efficient organisms for the production of chemicals and biofuels. Yet, the productivity of the cell has been low for commercial application. Cyanobacterial photobiotransformations utilize photosynthetic electrons to form reducing equivalents, such as NADPH-to-fuel biocatalytic reactions. These photobiotransformations are a measure to which extent photosynthetic electrons can be deviated toward heterologous biotechnological processes, such as the production of biofuels. By expressing oxidoreductases, such as YqjM from Bacillus subtilis in Synechocystis sp. PCC 6803, a high specific activity was obtained in the reduction of maleimides. Here, we investigated the possibility to accelerate the NAD(P)H-consuming redox reactions by addition of carbohydrates as exogenous carbon sources such as D-Glucose under light and darkness. RESULTS A 1.7-fold increase of activity (150 µmol min-1 gDCW-1) was observed upon addition of D-Glucose at an OD750 = 2.5 (DCW = 0.6 g L-1) in the biotransformation of 2-methylmaleimide. The stimulating effect of D-Glucose was also observed at higher cell densities in light and dark conditions as well as in the reduction of other substrates. No increase in both effective photosynthetic yields of Photosystem II and Photosystem I was found upon D-Glucose addition. However, we observed higher NAD(P)H fluorescence when D-Glucose was supplemented, suggesting increased glycolytic activity. Moreover, the system was scaled-up (working volume of 200 mL) in an internally illuminated Bubble Column Reactor exhibiting a 2.4-fold increase of specific activity under light-limited conditions. CONCLUSIONS Results show that under photoautotrophic conditions at a specific activity of 90 µmol min-1 gDCW-1, the ene-reductase YqjM in Synechocystis sp. PCC 6803 is not NAD(P)H saturated, which is an indicator that an increase of the rates of heterologous electron consuming processes for catalysis and biofuel production will require funnelling further reducing power from the photosynthetic chain toward heterologous processes.
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Affiliation(s)
- Giovanni Davide Barone
- grid.410413.30000 0001 2294 748XBiocatalysis and Protein Engineering, Institute of Molecular Biotechnology, Graz University of Technology, 8010 Graz, Austria ,grid.5808.50000 0001 1503 7226i3S - Instituto de Investigação e Inovação em Saúde, IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal ,grid.5808.50000 0001 1503 7226Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, 4169-007 Porto, Portugal
| | - Michal Hubáček
- grid.1374.10000 0001 2097 1371Laboratory of Molecular Plant Biology, Department of Life Technologies, University of Turku, 20014 Turku, Finland
| | - Lenny Malihan-Yap
- grid.410413.30000 0001 2294 748XBiocatalysis and Protein Engineering, Institute of Molecular Biotechnology, Graz University of Technology, 8010 Graz, Austria
| | - Hanna C. Grimm
- grid.410413.30000 0001 2294 748XBiocatalysis and Protein Engineering, Institute of Molecular Biotechnology, Graz University of Technology, 8010 Graz, Austria
| | - Lauri Nikkanen
- grid.1374.10000 0001 2097 1371Laboratory of Molecular Plant Biology, Department of Life Technologies, University of Turku, 20014 Turku, Finland
| | - Catarina C. Pacheco
- grid.5808.50000 0001 1503 7226i3S - Instituto de Investigação e Inovação em Saúde, IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal
| | - Paula Tamagnini
- grid.5808.50000 0001 1503 7226i3S - Instituto de Investigação e Inovação em Saúde, IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal ,grid.5808.50000 0001 1503 7226Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, 4169-007 Porto, Portugal
| | - Yagut Allahverdiyeva
- grid.1374.10000 0001 2097 1371Laboratory of Molecular Plant Biology, Department of Life Technologies, University of Turku, 20014 Turku, Finland
| | - Robert Kourist
- grid.410413.30000 0001 2294 748XBiocatalysis and Protein Engineering, Institute of Molecular Biotechnology, Graz University of Technology, 8010 Graz, Austria
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6
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Burnap RL. Cyanobacterial Bioenergetics in Relation to Cellular Growth and Productivity. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2023; 183:25-64. [PMID: 36764956 DOI: 10.1007/10_2022_215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
Cyanobacteria, the evolutionary originators of oxygenic photosynthesis, have the capability to convert CO2, water, and minerals into biomass using solar energy. This process is driven by intricate bioenergetic mechanisms that consist of interconnected photosynthetic and respiratory electron transport chains coupled. Over the last few decades, advances in physiochemical analysis, molecular genetics, and structural analysis have enabled us to gain a more comprehensive understanding of cyanobacterial bioenergetics. This includes the molecular understanding of the primary energy conversion mechanisms as well as photoprotective and other dissipative mechanisms that prevent photodamage when the rates of photosynthetic output, primarily in the form of ATP and NADPH, exceed the rates that cellular assimilatory processes consume these photosynthetic outputs. Despite this progress, there is still much to learn about the systems integration and the regulatory circuits that control expression levels for optimal cellular abundance and activity of the photosynthetic complexes and the cellular components that convert their products into biomass. With an improved understanding of these regulatory principles and mechanisms, it should be possible to optimally modify cyanobacteria for enhanced biotechnological purposes.
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Affiliation(s)
- Robert L Burnap
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, USA.
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7
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Chen AY, Ku JT, Tsai TP, Hung JJ, Hung BC, Lan EI. Metabolic Engineering Design Strategies for Increasing Carbon Fluxes Relevant for Biosynthesis in Cyanobacteria. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2023; 183:105-144. [PMID: 37093259 DOI: 10.1007/10_2023_218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
Cyanobacteria are promising microbial cell factories for the direct production of biochemicals and biofuels from CO2. Through genetic and metabolic engineering, they can be modified to produce a variety of both natural and non-natural compounds. To enhance the yield of these products, various design strategies have been developed. In this chapter, strategies used to enhance metabolic fluxes towards common precursors used in biosynthesis, including pyruvate, acetyl-CoA, malonyl-CoA, TCA cycle intermediates, and aromatics, are discussed. Additionally, strategies related to cofactor availability and mixotrophic conditions for bioproduction are also summarize.
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Affiliation(s)
- Arvin Y Chen
- Institute of Molecular Medicine and Bioengineering, National Yang Ming Chiao Tung University, Hsinchu City, Taiwan
| | - Jason T Ku
- Institute of Molecular Medicine and Bioengineering, National Yang Ming Chiao Tung University, Hsinchu City, Taiwan
| | - Teresa P Tsai
- Institute of Biomedical Engineering, National Yang Ming Chiao Tung University, Hsinchu City, Taiwan
| | - Jenny J Hung
- Institute of Molecular Medicine and Bioengineering, National Yang Ming Chiao Tung University, Hsinchu City, Taiwan
| | - Billy C Hung
- Institute of Molecular Medicine and Bioengineering, National Yang Ming Chiao Tung University, Hsinchu City, Taiwan
| | - Ethan I Lan
- Department of Biological Science and Technology, National Yang Ming Chiao Tung University, Hsinchu City, Taiwan.
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8
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Spasic J, Oliveira P, Pacheco C, Kourist R, Tamagnini P. Engineering cyanobacterial chassis for improved electron supply toward a heterologous ene-reductase. J Biotechnol 2022; 360:152-159. [PMID: 36370921 DOI: 10.1016/j.jbiotec.2022.11.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 11/07/2022] [Accepted: 11/08/2022] [Indexed: 11/10/2022]
Abstract
Cyanobacteria are noteworthy hosts for industrially relevant redox reactions, owing to a light-driven cofactor recycling system using water as electron donor. Customizing Synechocystis sp. PCC 6803 chassis by redirecting electron flow offers a particularly interesting approach to further improve light-driven biotransformations. Therefore, different chassis expressing the heterologous ene-reductase YqjM (namely ΔhoxYH, Δflv3, ΔndhD2 and ΔhoxYHΔflv3) were generated/evaluated. The results showed the robustness of the chassis, that exhibited growth and oxygen evolution rates similar to Synechocystis wild-type, even when expressing YqjM. By engineering the electron flow, the YqjM light-driven stereoselective reduction of 2-methylmaleimide to 2-methylsuccinimide was significantly enhanced in all chassis. In the best performing chassis (ΔhoxYH, lacking an active bidirectional hydrogenase) a 39 % increase was observed, reaching an in vivo specific activity of 116 U gDCW-1 and an initial reaction rate of 16.7 mM h-1. In addition, the presence of the heterologous YqjM mitigated substrate toxicity, and the conversion of 2-methylmaleimide increased oxygen evolution rates, in particular at higher light intensity. In conclusion, this work demonstrates that rational engineering of electron transfer pathways is a valid strategy to increase in vivo specific activities and initial reaction rates in cyanobacterial chassis harboring oxidoreductases.
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Affiliation(s)
- Jelena Spasic
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal; Institute of Molecular Biotechnology, Graz University of Technology, Petersgasse 14, 8010 Graz, Austria
| | - Paulo Oliveira
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal
| | - Catarina Pacheco
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal
| | - Robert Kourist
- Institute of Molecular Biotechnology, Graz University of Technology, Petersgasse 14, 8010 Graz, Austria
| | - Paula Tamagnini
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal; Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal.
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9
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Hatano J, Kusama S, Tanaka K, Kohara A, Miyake C, Nakanishi S, Shimakawa G. NADPH production in dark stages is critical for cyanobacterial photocurrent generation: a study using mutants deficient in oxidative pentose phosphate pathway. PHOTOSYNTHESIS RESEARCH 2022; 153:113-120. [PMID: 35182311 DOI: 10.1007/s11120-022-00903-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Accepted: 01/16/2022] [Indexed: 06/14/2023]
Abstract
Live cyanobacteria and algae integrated onto an extracellular electrode can generate a light-induced current (i.e., a photocurrent). Although the photocurrent is expected to be correlated with the redox environment of the photosynthetic cells, the relationship between the photocurrent and the cellular redox state is poorly understood. Here, we investigated the effect of the reduced nicotinamide adenine dinucleotide phosphate [NADP(H)] redox level of cyanobacterial cells (before light exposure) on the photocurrent using several mutants (Δzwf, Δgnd, and ΔglgP) deficient in the oxidative pentose phosphate (OPP) pathway, which is the metabolic pathway that produces NADPH in darkness. The NAD(P)H redox level and photocurrent in the cyanobacterium Synechocystis sp. PCC 6803 were measured noninvasively. Dysfunction of the OPP pathway led to oxidation of the photosynthetic NADPH pool in darkness. In addition, photocurrent induction was retarded and the current density was lower in Δzwf, Δgnd, and ΔglgP than in wild-type cells. Exogenously added glucose compensated the phenotype of ΔglgP and drove the OPP pathway in the mutant, resulting in an increase in the photocurrent. The results indicated that NADPH accumulated by the OPP pathway before illumination is a key factor for the generation of a photocurrent. In addition, measuring the photocurrent can be a non-invasive approach to estimate the cellular redox level related to NADP(H) pool in cyanobacteria.
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Affiliation(s)
- Jiro Hatano
- Research Center for Solar Energy Chemistry, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka, 560-8631, Japan
| | - Shoko Kusama
- Research Center for Solar Energy Chemistry, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka, 560-8631, Japan
| | - Kenya Tanaka
- Research Center for Solar Energy Chemistry, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka, 560-8631, Japan
- Engineering Biology Research Center, Kobe University, Kobe, Japan
| | - Ayaka Kohara
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501, Japan
| | - Chikahiro Miyake
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501, Japan
| | - Shuji Nakanishi
- Research Center for Solar Energy Chemistry, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka, 560-8631, Japan.
- Innovative Catalysis Science Division, Institute for Open and Transdisciplinary Research Initiatives, Osaka University, Suita, Osaka, 565-0871, Japan.
| | - Ginga Shimakawa
- Research Center for Solar Energy Chemistry, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka, 560-8631, Japan.
- Department of Bioscience, School of Biological and Environmental Sciences, Kwansei-Gakuin University, 2-1 Gakuen, Sanda, Hyogo, 669-1337, Japan.
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10
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Kusama S, Miyake C, Nakanishi S, Shimakawa G. Dissection of respiratory and cyclic electron transport in Synechocystis sp. PCC 6803. JOURNAL OF PLANT RESEARCH 2022; 135:555-564. [PMID: 35680769 DOI: 10.1007/s10265-022-01401-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 06/01/2022] [Indexed: 06/15/2023]
Abstract
Cyclic electron transport (CET) is an attractive hypothesis for regulating photosynthetic electron transport and producing the additional ATP in oxygenic phototrophs. The concept of CET has been established in the last decades, and it is proposed to function in the progenitor of oxygenic photosynthesis, cyanobacteria. The in vivo activity of CET is frequently evaluated either from the redox state of the reaction center chlorophyll in photosystem (PS) I, P700, in the absence of PSII activity or by comparing PSI and PSII activities through the P700 redox state and chlorophyll fluorescence, respectively. The evaluation of CET activity, however, is complicated especially in cyanobacteria, where CET shares the intersystem chain, including plastoquinone, cytochrome b6/f complex, plastocyanin, and cytochrome c6, with photosynthetic linear electron transport (LET) and respiratory electron transport (RET). Here we sought to distinguish the in vivo electron transport rates in RET and CET in the cyanobacterium Synechocystis sp. PCC 6803. The reduction rate of oxidized P700 (P700+) decreased to less than 10% when PSII was inhibited, indicating that PSII is the dominant electron source to PSI but P700+ is also reduced by electrons derived from other sources. The oxidative pentose phosphate (OPP) pathway functions as the dominant electron source for RET, which was found to be inhibited by glycolaldehyde (GA). In the condition where the OPP pathway and respiratory terminal oxidases were inhibited by GA and KCN, the P700+ reduction rate was less than 1% of that without any inhibitors. This study indicate that the electron transport to PSI when PSII is inhibited is dominantly derived from the OPP pathway in Synechocystis sp. PCC 6803.
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Affiliation(s)
- Shoko Kusama
- Research Center for Solar Energy Chemistry, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka, 560-8531, Japan
| | - Chikahiro Miyake
- Department of Biological and Environmental Science, Faculty of Agriculture, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe, 657-8501, Japan
| | - Shuji Nakanishi
- Research Center for Solar Energy Chemistry, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka, 560-8531, Japan
| | - Ginga Shimakawa
- Research Center for Solar Energy Chemistry, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka, 560-8531, Japan.
- Department of Bioscience, School of Biological and Environmental Sciences, Kwansei-Gakuin University, 2-1 Gakuen, Sanda, Hyogo, 669-1337, Japan.
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Order-of-magnitude enhancement in photocurrent generation of Synechocystis sp. PCC 6803 by outer membrane deprivation. Nat Commun 2022; 13:3067. [PMID: 35654796 PMCID: PMC9163127 DOI: 10.1038/s41467-022-30764-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Accepted: 05/17/2022] [Indexed: 12/24/2022] Open
Abstract
Biophotovoltaics (BPV) generates electricity from reducing equivalent(s) produced by photosynthetic organisms by exploiting a phenomenon called extracellular electron transfer (EET), where reducing equivalent(s) is transferred to external electron acceptors. Although cyanobacteria have been extensively studied for BPV because of their high photosynthetic activity and ease of handling, their low EET activity poses a limitation. Here, we show an order-of-magnitude enhancement in photocurrent generation of the cyanobacterium Synechocystis sp. PCC 6803 by deprivation of the outer membrane, where electrons are suggested to stem from pathway(s) downstream of photosystem I. A marked enhancement of EET activity itself is verified by rapid reduction of exogenous electron acceptor, ferricyanide. The extracellular organic substances, including reducing equivalent(s), produced by this cyanobacterium serve as respiratory substrates for other heterotrophic bacteria. These findings demonstrate that the outer membrane is a barrier that limits EET. Therefore, depriving this membrane is an effective approach to exploit the cyanobacterial reducing equivalent(s). The low extracellular electron transfer activity hampers the application of cyanobacteria in biophotovoltaics. Here, the authors report an order-of-magnitude enhancement in photocurrent generation of the cyanobacterium by deprivation of the outer cell membrane.
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Ogawa T, Suzuki K, Sonoike K. Respiration Interacts With Photosynthesis Through the Acceptor Side of Photosystem I, Reflected in the Dark-to-Light Induction Kinetics of Chlorophyll Fluorescence in the Cyanobacterium Synechocystis sp. PCC 6803. FRONTIERS IN PLANT SCIENCE 2021; 12:717968. [PMID: 34394172 PMCID: PMC8355559 DOI: 10.3389/fpls.2021.717968] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 07/05/2021] [Indexed: 05/08/2023]
Abstract
In cyanobacteria, the photosynthetic prokaryotes, direct interaction between photosynthesis and respiration exists at plastoquinone (PQ) pool, which is shared by the two electron transport chains. Another possible point of intersection of the two electron transport chains is NADPH, which is the major electron donor to the respiratory chain as well as the final product of the photosynthetic chain. Here, we showed that the redox state of NADPH in the dark affected chlorophyll fluorescence induction in the cyanobacterium Synechocystis sp. PCC 6803 in a quantitative manner. Accumulation of the reduced NADPH in the dark due to the defect in type 1 NAD(P)H dehydrogenase complex in the respiratory chain resulted in the faster rise to the peak in the dark-to-light induction of chlorophyll fluorescence, while depletion of NADPH due to the defect in pentose phosphate pathway resulted in the delayed appearance of the initial peak in the induction kinetics. There was a strong correlation between the dark level of NADPH determined by its fluorescence and the peak position of the induction kinetics of chlorophyll fluorescence. These results indicate that photosynthesis interacts with respiration through NADPH, which enable us to monitor the redox condition of the acceptor side of photosystem I by simple measurements of chlorophyll fluorescence induction in cyanobacteria.
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