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Xiong W, Peng Y, Ma W, Xu X, Zhao Y, Wu J, Tang R. Microalgae-material hybrid for enhanced photosynthetic energy conversion: a promising path towards carbon neutrality. Natl Sci Rev 2023; 10:nwad200. [PMID: 37671320 PMCID: PMC10476897 DOI: 10.1093/nsr/nwad200] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2023] [Revised: 05/10/2023] [Accepted: 07/02/2023] [Indexed: 09/07/2023] Open
Abstract
Photosynthetic energy conversion for high-energy chemicals generation is one of the most viable solutions in the quest for sustainable energy towards carbon neutrality. Microalgae are fascinating photosynthetic organisms, which can directly convert solar energy into chemical energy and electrical energy. However, microalgal photosynthetic energy has not yet been applied on a large scale due to the limitation of their own characteristics. Researchers have been inspired to couple microalgae with synthetic materials via biomimetic assembly and the resulting microalgae-material hybrids have become more robust and even perform new functions. In the past decade, great progress has been made in microalgae-material hybrids, such as photosynthetic carbon dioxide fixation, photosynthetic hydrogen production, photoelectrochemical energy conversion and even biochemical energy conversion for biomedical therapy. The microalgae-material hybrid offers opportunities to promote artificially enhanced photosynthesis research and synchronously inspires investigation of biotic-abiotic interface manipulation. This review summarizes current construction methods of microalgae-material hybrids and highlights their implication in energy and health. Moreover, we discuss the current problems and future challenges for microalgae-material hybrids and the outlook for their development and applications. This review will provide inspiration for the rational design of the microalgae-based semi-natural biohybrid and further promote the disciplinary fusion of material science and biological science.
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Affiliation(s)
- Wei Xiong
- School of Chemistry and Chemical Engineering, Nanchang University, Nanchang 330031, China
| | - Yiyan Peng
- School of Chemistry and Chemical Engineering, Nanchang University, Nanchang 330031, China
| | - Weimin Ma
- College of Life Sciences, Shanghai Normal University, Shanghai 200234, China
| | - Xurong Xu
- Department of Chemistry, Zhejiang University, Hangzhou 310058, China
- Qiushi Academy for Advanced Studies, Zhejiang University, Hangzhou 310027, China
| | - Yueqi Zhao
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou 310016, China
| | - Jinhui Wu
- State Key Laboratory of Pharmaceutical Biotechnology, Medical School & School of Life Sciences, Nanjing University, Nanjing 210093, China
| | - Ruikang Tang
- Department of Chemistry, Zhejiang University, Hangzhou 310058, China
- Qiushi Academy for Advanced Studies, Zhejiang University, Hangzhou 310027, China
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2
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Xu W, Wang Y. Post-translational Modifications of Serine/Threonine and Histidine Kinases and Their Roles in Signal Transductions in Synechocystis Sp. PCC 6803. Appl Biochem Biotechnol 2020; 193:687-716. [PMID: 33159456 DOI: 10.1007/s12010-020-03435-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 09/29/2020] [Indexed: 11/25/2022]
Abstract
Cyanobacterium Synechocystis sp. PCC 6803, a popular model organism for researches in photosynthesis and biofuel production, contains plant-like photosynthetic machineries which significantly contribute to global carbon fixation. There are 12 eukaryotic-type Ser/Thr kinases (SpkA-L) and 49 His kinases (Hik1-49) of two-component systems in the genome of Synechocystis sp. PCC 6803. They are the key regulators in sensing and transmitting stimuli including light- and glucose-mediate signal transduction. Proteomic studies were able to identify all the kinases. The majority of kinases no matter whether they have a predicted transmembrane domain were identified in the membrane fractions. Six Ser/Thr kinases (SpkA-D, F and G) and ten His kinases (Hik4, 12, 14, 21, 26-27, 29, 36, 43, and 46) were identified to have one or more of the three types of post-translational modifications: phosphorylation, acetylation, and thiol oxidation. Interestingly, SpkG has the phosphorylatable threonine residue that was aligned with the phosphorylated threonine residue in the activation loop of human CDK7, demonstrating conserved phosphorylation between cyanobacterial and human kinases. Transcriptomics and proteomics revealed differential expression of the kinases in heterotrophic and photoheterotrophic compared with photoautotrophic conditions, indicating their roles in regulating the growth modes of cyanobacteria. In summary, this review focuses on the discussions on post-transcriptional modifications, transcriptomic, and proteomic studies of Ser/Thr and His kinases. This together with our published review in 2019 present a complete story of an overview of sequences, domain architectures, and biochemical and physiological functions of cyanobacterial kinases with adequate details in the context of high throughput systems. We also emphasize the importance of discovering upstream molecules and substrates to understand the exact functions of the kinases in vivo. As an attempt, a model is proposed in which Hik31, His33, Sll1334, and IcfG are hypothesized to be critical for switching between autotrophic and heterotrophic modes based on the results from the phenotypes of the gene knockout strains combined with their post-translational modifications, and gene expression profiles.
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Affiliation(s)
- Wu Xu
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, LA, 70504, USA.
| | - Yingchun Wang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, No.1 West Beichen Rd, Beijing, 100101, China.
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Chittora D, Meena M, Barupal T, Swapnil P. Cyanobacteria as a source of biofertilizers for sustainable agriculture. Biochem Biophys Rep 2020; 22:100737. [PMID: 32083191 PMCID: PMC7021550 DOI: 10.1016/j.bbrep.2020.100737] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 01/04/2020] [Accepted: 01/24/2020] [Indexed: 12/29/2022] Open
Abstract
Continuous increase in global human population and depletion of natural resources of energy posing threat to environment needs, sustainable supply of food and energy. The most ecofriendly approach 'green technology' has been exploited for biofertilizer preparation. Cyanobacteria are the most successful and sustained prokaryotic organism during the course of evolution. They are considered as one of the primitive life forms found on our planet. Cyanobacteria are emerging candidates for efficiently conversion of radiant energy into chemical energy. This biological system produces oxygen as a by-product. Cyanobacterial biomass can also be used for the large scale production of food, energy, biofertilizers, secondary metabolites, cosmetics and medicines. Therefore, cyanobacteria are used in ecofriendly sustainable agricultural practice for production of biomass of very high value and decreasing the level of CO2. This review article describes the methods of mass production of cyanobacterial biofertilizers and their applications in agriculture and industrial level.
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Affiliation(s)
- Deepali Chittora
- Department of Botany, Mohanlal Sukhadia University, Udaipur, 313001, Rajasthan, India
| | - Mukesh Meena
- Department of Botany, Mohanlal Sukhadia University, Udaipur, 313001, Rajasthan, India
| | - Tansukh Barupal
- Department of Botany, Mohanlal Sukhadia University, Udaipur, 313001, Rajasthan, India
| | - Prashant Swapnil
- International Centre for Genetic Engineering and Biotechnology, New Delhi, 110067, India
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Grattieri M, Beaver K, Gaffney EM, Dong F, Minteer SD. Advancing the fundamental understanding and practical applications of photo-bioelectrocatalysis. Chem Commun (Camb) 2020; 56:8553-8568. [PMID: 32578607 DOI: 10.1039/d0cc02672g] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Photo-bioelectrocatalysis combines the natural and highly sophisticated process of photosynthesis in biological entities with an abiotic electrode surface, to perform semi-artificial photosynthesis. However, challenges must be overcome, from the establishment and understanding of the photoexcited electron harvesting process at the electrode to the electrochemical characterization of these biotic/abiotic systems, and their subsequent tuning for enhancing energy generation (chemical and/or electrical). This Feature Article discusses the various approaches utilized to tackle these challenges, particularly focusing on powerful multi-disciplinary approaches for understanding and improving photo-bioelectrocatalysis. Among them is the combination of experimental evidence and quantum mechanical calculations, the use of bioinformatics to understand photo-bioelectrocatalysis at a metabolic level, or bioengineering to improve and facilitate photo-bioelectrocatalysis. Key aspects for the future development of photo-bioelectrocatalysis are presented alongside future research needs and promising applications of semi-artificial photosynthesis.
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Affiliation(s)
- Matteo Grattieri
- Department of Chemistry, University of Utah, 315 S 1400 E Rm 2020, Salt Lake City, UT 84112, USA.
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Pernil R, Schleiff E. Metalloproteins in the Biology of Heterocysts. Life (Basel) 2019; 9:E32. [PMID: 30987221 PMCID: PMC6616624 DOI: 10.3390/life9020032] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 03/18/2019] [Accepted: 03/28/2019] [Indexed: 12/15/2022] Open
Abstract
Cyanobacteria are photoautotrophic microorganisms present in almost all ecologically niches on Earth. They exist as single-cell or filamentous forms and the latter often contain specialized cells for N₂ fixation known as heterocysts. Heterocysts arise from photosynthetic active vegetative cells by multiple morphological and physiological rearrangements including the absence of O₂ evolution and CO₂ fixation. The key function of this cell type is carried out by the metalloprotein complex known as nitrogenase. Additionally, many other important processes in heterocysts also depend on metalloproteins. This leads to a high metal demand exceeding the one of other bacteria in content and concentration during heterocyst development and in mature heterocysts. This review provides an overview on the current knowledge of the transition metals and metalloproteins required by heterocysts in heterocyst-forming cyanobacteria. It discusses the molecular, physiological, and physicochemical properties of metalloproteins involved in N₂ fixation, H₂ metabolism, electron transport chains, oxidative stress management, storage, energy metabolism, and metabolic networks in the diazotrophic filament. This provides a detailed and comprehensive picture on the heterocyst demands for Fe, Cu, Mo, Ni, Mn, V, and Zn as cofactors for metalloproteins and highlights the importance of such metalloproteins for the biology of cyanobacterial heterocysts.
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Affiliation(s)
- Rafael Pernil
- Institute for Molecular Biosciences, Goethe University Frankfurt, Max-von-Laue-Straβe 9, 60438 Frankfurt am Main, Germany.
| | - Enrico Schleiff
- Institute for Molecular Biosciences, Goethe University Frankfurt, Max-von-Laue-Straβe 9, 60438 Frankfurt am Main, Germany.
- Frankfurt Institute for Advanced Studies, Ruth-Moufang-Straße 1, 60438 Frankfurt am Main, Germany.
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Max-von-Laue-Straβe 15, 60438 Frankfurt am Main, Germany.
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Xu W, Wang Y. Sequences, Domain Architectures, and Biological Functions of the Serine/Threonine and Histidine Kinases in Synechocystis sp. PCC 6803. Appl Biochem Biotechnol 2019; 188:1022-1065. [PMID: 30778824 DOI: 10.1007/s12010-019-02971-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 02/01/2019] [Indexed: 01/08/2023]
Abstract
The cyanobacterium Synechocystis sp. PCC 6803 (hereafter Synechocystis) is a photoautotrophic prokaryote with plant-like photosynthetic machineries which significantly contribute to global carbon fixation and atmospheric oxygen production. Because of the relatively short cell doubling time, small size of the genome, and the ease for genetic manipulation, Synechocystis is a popular model organism for studies including photosynthesis and biofuel production. The cyanobacterium contains 12 eukaryotic type Ser/Thr kinases (SpkA-L) and 49 histidine kinases (Hik1-47 and Sll1334 and Sll5060 are named as Hik48 and Hik49, respectively, in this review) of the two-component system. All SpkA-L kinases have a eukaryotic kinase DFG signature in their A-loops. Based on the types of the kinase domains, the Spks can be separated into three groups: one group contains SpkA and SpkG which are related to human kinases, while SpkH-L are in another group that is distinct from human kinases. The third group contains SpkB-F which are between the first two groups. Four histidine kinases (Hiks17, 36, 45, and 48) lack a clear histidine kinase domain, and the conserved phosphorylatable histidine residue could not be identified for six histidine kinases (Hiks11, 18, 29, 37, 39, and 43) even though they have clear histidine kinase domains. Each of the remaining 39 has a histidine kinase domain with the conserved histidine residue. Eight hybrid histidine kinases contain one or two receiver domains, and they all, except Hik25 (Slr0222), have the conserved phosphorylatable aspartate. The disruptants of all kinases except hik13 and hik15 have been generated, and the majority of them have modest or no obvious phenotypes, indicating other kinases could functionally compensate the loss of a particular kinase. This review presents a comprehensive discussion including a spectrum of sequence, domain architecture, in vivo function, and proteomics investigations of Ser/Thr and histidine kinases. Understanding the sequences, domain architectures, and biology of the kinases will help to integrate "omic" data to clarify their exact biochemical functions.
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Affiliation(s)
- Wu Xu
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, LA, 70504, USA.
| | - Yingchun Wang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, No.1 West Beichen Rd., Beijing, 100101, China.
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Homogeneous electrocatalytic oxidation of ammonia to N 2 under mild conditions. Proc Natl Acad Sci U S A 2019; 116:2849-2853. [PMID: 30655346 DOI: 10.1073/pnas.1813368116] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We report that ruthenium polypyridyl complexes can catalyze ammonia oxidation to dinitrogen at room temperature and ambient pressure. During bulk electrolysis experiments, gas chromatography and mass spectrometry analysis of the headspace in the electrochemical cell showed that dinitrogen and dihydrogen are generated from ammonia with high faradaic efficiencies. A proposed mechanism where a hydrazine complex is the initial N-N bonded intermediate is supported by chemical and electrochemical experiments. This is a well-defined system for homogeneous electrocatalytic ammonia oxidation. It establishes a platform for answering mechanistic questions relevant to using ammonia to store and distribute renewable energy.
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Shimakawa G, Miyake C. Oxidation of P700 Ensures Robust Photosynthesis. FRONTIERS IN PLANT SCIENCE 2018; 9:1617. [PMID: 30459798 PMCID: PMC6232666 DOI: 10.3389/fpls.2018.01617] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 10/18/2018] [Indexed: 05/18/2023]
Abstract
In the light, photosynthetic cells can potentially suffer from oxidative damage derived from reactive oxygen species. Nevertheless, a variety of oxygenic photoautotrophs, including cyanobacteria, algae, and plants, manage their photosynthetic systems successfully. In the present article, we review previous research on how these photoautotrophs safely utilize light energy for photosynthesis without photo-oxidative damage to photosystem I (PSI). The reaction center chlorophyll of PSI, P700, is kept in an oxidized state in response to excess light, under high light and low CO2 conditions, to tune the light utilization and dissipate the excess photo-excitation energy in PSI. Oxidation of P700 is co-operatively regulated by a number of molecular mechanisms on both the electron donor and acceptor sides of PSI. The strategies to keep P700 oxidized are diverse among a variety of photoautotrophs, which are evolutionarily optimized for their ecological niche.
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Affiliation(s)
- Ginga Shimakawa
- Department of Biological and Environmental Science, Faculty of Agriculture, Graduate School of Agricultural Science, Kobe University, Kobe, Japan
| | - Chikahiro Miyake
- Department of Biological and Environmental Science, Faculty of Agriculture, Graduate School of Agricultural Science, Kobe University, Kobe, Japan
- Core Research for Environmental Science and Technology, Japan Science and Technology Agency, Tokyo, Japan
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Nies F, Wörner S, Wunsch N, Armant O, Sharma V, Hesselschwerdt A, Falk F, Weber N, Weiß J, Trautmann A, Posten C, Prakash T, Lamparter T. Characterization of Phormidium lacuna strains from the North Sea and the Mediterranean Sea for biotechnological applications. Process Biochem 2017. [DOI: 10.1016/j.procbio.2017.05.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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10
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Liu LN. Distribution and dynamics of electron transport complexes in cyanobacterial thylakoid membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1857:256-65. [PMID: 26619924 PMCID: PMC4756276 DOI: 10.1016/j.bbabio.2015.11.010] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Revised: 11/17/2015] [Accepted: 11/19/2015] [Indexed: 12/24/2022]
Abstract
The cyanobacterial thylakoid membrane represents a system that can carry out both oxygenic photosynthesis and respiration simultaneously. The organization, interactions and mobility of components of these two electron transport pathways are indispensable to the biosynthesis of thylakoid membrane modules and the optimization of bioenergetic electron flow in response to environmental changes. These are of fundamental importance to the metabolic robustness and plasticity of cyanobacteria. This review summarizes our current knowledge about the distribution and dynamics of electron transport components in cyanobacterial thylakoid membranes. Global understanding of the principles that govern the dynamic regulation of electron transport pathways in nature will provide a framework for the design and synthetic engineering of new bioenergetic machinery to improve photosynthesis and biofuel production. This article is part of a Special Issue entitled: Organization and dynamics of bioenergetic systems in bacteria, edited by Conrad Mullineaux. Cyanobacterial thylakoid membranes carry out both oxygenic photosynthesis and respiration. Electron transport components are located in the thylakoid membrane and functionally coordinate with each other. Distribution and dynamics of electron transport components are physiologically regulated in response to environmental change.
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Affiliation(s)
- Lu-Ning Liu
- Institute of Integrative Biology, University of Liverpool, Crown Street, Liverpool L69 7ZB, United Kingdom.
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11
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Schaffner I, Hofbauer S, Krutzler M, Pirker KF, Bellei M, Stadlmayr G, Mlynek G, Djinovic-Carugo K, Battistuzzi G, Furtmüller PG, Daims H, Obinger C. Dimeric chlorite dismutase from the nitrogen-fixing cyanobacterium Cyanothece sp. PCC7425. Mol Microbiol 2015; 96:1053-68. [PMID: 25732258 PMCID: PMC4973843 DOI: 10.1111/mmi.12989] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/01/2015] [Indexed: 11/28/2022]
Abstract
It is demonstrated that cyanobacteria (both azotrophic and non-azotrophic) contain heme b oxidoreductases that can convert chlorite to chloride and molecular oxygen (incorrectly denominated chlorite 'dismutase', Cld). Beside the water-splitting manganese complex of photosystem II, this metalloenzyme is the second known enzyme that catalyses the formation of a covalent oxygen-oxygen bond. All cyanobacterial Clds have a truncated N-terminus and are dimeric (i.e. clade 2) proteins. As model protein, Cld from Cyanothece sp. PCC7425 (CCld) was recombinantly produced in Escherichia coli and shown to efficiently degrade chlorite with an activity optimum at pH 5.0 [kcat 1144 ± 23.8 s(-1), KM 162 ± 10.0 μM, catalytic efficiency (7.1 ± 0.6) × 10(6) M(-1) s(-1)]. The resting ferric high-spin axially symmetric heme enzyme has a standard reduction potential of the Fe(III)/Fe(II) couple of -126 ± 1.9 mV at pH 7.0. Cyanide mediates the formation of a low-spin complex with k(on) = (1.6 ± 0.1) × 10(5) M(-1) s(-1) and k(off) = 1.4 ± 2.9 s(-1) (KD ∼ 8.6 μM). Both, thermal and chemical unfolding follows a non-two-state unfolding pathway with the first transition being related to the release of the prosthetic group. The obtained data are discussed with respect to known structure-function relationships of Clds. We ask for the physiological substrate and putative function of these O2 -producing proteins in (nitrogen-fixing) cyanobacteria.
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Affiliation(s)
- Irene Schaffner
- Department of Chemistry, Division of Biochemistry, BOKU - University of Natural Resources and Life Sciences, Muthgasse 18, A-1190, Vienna, Austria
| | - Stefan Hofbauer
- Department of Chemistry, Division of Biochemistry, BOKU - University of Natural Resources and Life Sciences, Muthgasse 18, A-1190, Vienna, Austria.,Department for Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
| | - Michael Krutzler
- Department of Chemistry, Division of Biochemistry, BOKU - University of Natural Resources and Life Sciences, Muthgasse 18, A-1190, Vienna, Austria
| | - Katharina F Pirker
- Department of Chemistry, Division of Biochemistry, BOKU - University of Natural Resources and Life Sciences, Muthgasse 18, A-1190, Vienna, Austria
| | - Marzia Bellei
- Department of Life Sciences, University of Modena and Reggio Emilia, 41125, Modena, Italy
| | - Gerhard Stadlmayr
- Department of Chemistry, Division of Biochemistry, BOKU - University of Natural Resources and Life Sciences, Muthgasse 18, A-1190, Vienna, Austria
| | - Georg Mlynek
- Department for Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
| | - Kristina Djinovic-Carugo
- Department for Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria.,Department of Biochemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, 1000, Ljubljana, Slovenia
| | - Gianantonio Battistuzzi
- Department of Chemistry and Geology, University of Modena and Reggio Emilia, 41125, Modena, Italy
| | - Paul G Furtmüller
- Department of Chemistry, Division of Biochemistry, BOKU - University of Natural Resources and Life Sciences, Muthgasse 18, A-1190, Vienna, Austria
| | - Holger Daims
- Department of Microbiology and Ecosystem Science, Division of Microbial Ecology, University of Vienna, Vienna, Austria
| | - Christian Obinger
- Department of Chemistry, Division of Biochemistry, BOKU - University of Natural Resources and Life Sciences, Muthgasse 18, A-1190, Vienna, Austria
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Qi Z, Yang H, Xia X, Wang W, Yu X. High strength vinegar fermentation by Acetobacter pasteurianus via enhancing alcohol respiratory chain. BIOTECHNOL BIOPROC E 2014. [DOI: 10.1007/s12257-013-0727-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Hayashi R, Shimakawa G, Shaku K, Shimizu S, Akimoto S, Yamamoto H, Amako K, Sugimoto T, Tamoi M, Makino A, Miyake C. O2-dependent large electron flow functioned as an electron sink, replacing the steady-state electron flux in photosynthesis in the cyanobacterium Synechocystis sp. PCC 6803, but not in the cyanobacterium Synechococcus sp. PCC 7942. Biosci Biotechnol Biochem 2014; 78:384-93. [PMID: 25036824 DOI: 10.1080/09168451.2014.882745] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
To determine whether alternative electron flow (AEF) can replace the photosynthetic electron flow in cyanobacteria, we used an open O2-electrode system to monitor O2-exchange over a long period. In air-grown Synechocystis sp. PCC 6803 (S. 6803(WT)), the quantum yield of PSII, Y(II), held even after photosynthesis was suppressed by CO2 shortage. The S. 6803 mutant, deficient in flavodiiron (FLV) proteins 1 and 3, showed the same phenotype as S. 6803(WT). In contrast, Y(II) decreased in Synechococcus sp. PCC 7942 (S. 7942). These results suggest that AEF functioned as the Y(II) in S. 6803 and replaced the photosynthetic electron flux. In contrast, the activity of AEF in S. 7942 was lower. The affinity of AEF for O2 in S. 6803 did not correspond to those of FLVs in bacteria or terminal oxidases in respiration. AEF might be driven by photorespiration.
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Affiliation(s)
- Ryosuke Hayashi
- a Department of Biological and Environmental Sciences, Faculty of Agriculture , Graduate School of Agricultural Science, Kobe University , Kobe , Japan
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Photobiological hydrogen production: Bioenergetics and challenges for its practical application. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY C-PHOTOCHEMISTRY REVIEWS 2013. [DOI: 10.1016/j.jphotochemrev.2013.05.001] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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15
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Xiong W, Yang Z, Zhai H, Wang G, Xu X, Ma W, Tang R. Alleviation of high light-induced photoinhibition in cyanobacteria by artificially conferred biosilica shells. Chem Commun (Camb) 2013; 49:7525-7. [DOI: 10.1039/c3cc42766h] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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17
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The AbrB2 autorepressor, expressed from an atypical promoter, represses the hydrogenase operon to regulate hydrogen production in Synechocystis strain PCC6803. J Bacteriol 2012; 194:5423-33. [PMID: 22865847 DOI: 10.1128/jb.00543-12] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
We have thoroughly investigated the abrB2 gene (sll0822) encoding an AbrB-like regulator in the wild-type strain of the model cyanobacterium Synechocystis strain PCC6803. We report that abrB2 is expressed from an active but atypical promoter that possesses an extended -10 element (TGTAATAT) that compensates for the absence of a -35 box. Strengthening the biological significance of these data, we found that the occurrence of an extended -10 promoter box and the absence of a -35 element are two well-conserved features in abrB2 genes from other cyanobacteria. We also show that AbrB2 is an autorepressor that is dispensable to cell growth under standard laboratory conditions. Furthermore, we demonstrate that AbrB2 also represses the hox operon, which encodes the Ni-Fe hydrogenase of biotechnological interest, and that the hox operon is weakly expressed even though it possesses the two sequences resembling canonical -10 and -35 promoter boxes. In both the AbrB2-repressed promoters of the abrB2 gene and the hox operon, we found a repeated DNA motif [TT-(N(5))-AAC], which could be involved in AbrB2 repression. Supporting this hypothesis, we found that a TT-to-GG mutation of one of these elements increased the activity of the abrB2 promoter. We think that our abrB2-deleted mutant with increased expression of the hox operon and hydrogenase activity, together with the reporter plasmids we constructed to analyze the abrB2 gene and the hox operon, will serve as useful tools to decipher the function and the regulation of hydrogen production in Synechocystis.
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Großkopf T, LaRoche J. Direct and Indirect Costs of Dinitrogen Fixation in Crocosphaera watsonii WH8501 and Possible Implications for the Nitrogen Cycle. Front Microbiol 2012; 3:236. [PMID: 22833737 PMCID: PMC3401090 DOI: 10.3389/fmicb.2012.00236] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2012] [Accepted: 06/14/2012] [Indexed: 11/13/2022] Open
Abstract
The recent detection of heterotrophic nitrogen (N(2)) fixation in deep waters of the southern Californian and Peruvian OMZ questions our current understanding of marine N(2) fixation as a process confined to oligotrophic surface waters of the oceans. In experiments with Crocosphaera watsonii WH8501, a marine unicellular diazotrophic (N(2) fixing) cyanobacterium, we demonstrated that the presence of high nitrate concentrations (up to 800 μM) had no inhibitory effect on growth and N(2) fixation over a period of 2 weeks. In contrast, the environmental oxygen concentration significantly influenced rates of N(2) fixation and respiration, as well as carbon and nitrogen cellular content of C. watsonii over a 24-h period. Cells grown under lowered oxygen atmosphere (5%) had a higher nitrogenase activity and respired less carbon during the dark cycle than under normal oxygen atmosphere (20%). Respiratory oxygen drawdown during the dark period could be fully explained (104%) by energetic needs due to basal metabolism and N(2) fixation at low oxygen, while at normal oxygen these two processes could only account for 40% of the measured respiration rate. Our results revealed that under normal oxygen concentration most of the energetic costs during N(2) fixation (∼60%) are not derived from the process of N(2) fixation per se but rather from the indirect costs incurred for the removal of intracellular oxygen or by the reversal of oxidative damage (e.g., nitrogenase de novo synthesis). Theoretical calculations suggest a slight energetic advantage of N(2) fixation relative to assimilatory nitrate uptake, when oxygen supply is in balance with the oxygen requirement for cellular respiration (i.e., energy generation for basal metabolism and N(2) fixation). Taken together our results imply the existence of a niche for diazotrophic organisms inside oxygen minimum zones, which are predicted to further expand in the future ocean.
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Affiliation(s)
- Tobias Großkopf
- Research Division 2: Marine Biogeochemistry, Helmholtz-Centre for Ocean Research KielGEOMAR, Kiel, Germany
| | - Julie LaRoche
- Research Division 2: Marine Biogeochemistry, Helmholtz-Centre for Ocean Research KielGEOMAR, Kiel, Germany
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Mazor Y, Toporik H, Nelson N. Temperature-sensitive PSII and promiscuous PSI as a possible solution for sustainable photosynthetic hydrogen production. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1817:1122-6. [PMID: 22269125 DOI: 10.1016/j.bbabio.2012.01.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 01/02/2012] [Accepted: 01/07/2012] [Indexed: 10/14/2022]
Abstract
Sustainable hydrogen production in cyanobacteria becomes feasible as a result of our recent studies of the structure of photosystem I encoding operon in a marine phage. We demonstrated that the fused PsaJF subunit from the phage, substituted for the two separate subunits in Synechocystis, enabled the mutated PSI to accept electrons from additional electron donors such as respiratory cytochromes. In this way, a type of photorespiration was created in which the cell consumes organic material through respiratory processes and PSI serves as a terminal electron acceptor, substituting for cytochrome oxidase. We designed a hydrogen-producing bioreactor in which this type of photorespiration could utilize the organic material of the cell as an electron source for H(2) production. We propose, in parallel, to engineer cyanobacterial and/or algal strains with a temperature-sensitive PSII and enhanced respiration rates to achieve efficient and sustainable hydrogen production. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: from Natural to Artificial.
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Affiliation(s)
- Yuval Mazor
- Department of Biochemistry and Molecular Biology, Tel Aviv University, Tel Aviv, Israel
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Pisciotta JM, Zou Y, Baskakov IV. Role of the photosynthetic electron transfer chain in electrogenic activity of cyanobacteria. Appl Microbiol Biotechnol 2011; 91:377-85. [PMID: 21484209 DOI: 10.1007/s00253-011-3239-x] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Revised: 03/09/2011] [Accepted: 03/09/2011] [Indexed: 11/26/2022]
Abstract
Certain anaerobic bacteria, termed electrogens, produce an electric current when electrons from oxidized organic molecules are deposited to extracellular metal oxide acceptors. In these heterotrophic "metal breathers", the respiratory electron transport chain (R-ETC) works in concert with membrane-bound cytochrome oxidases to transfer electrons to the extracellular acceptors. The diversity of bacteria able to generate an electric current appears more widespread than previously thought, and aerobic phototrophs, including cyanobacteria, possess electrogenic activity. However, unlike heterotrophs, cyanobacteria electrogenic activity is light dependent, which suggests that a novel pathway could exist. To elucidate the electrogenic mechanism of cyanobacteria, the current studies used site-specific inhibitors to target components of the photosynthetic electron transport chain (P-ETC) and cytochrome oxidases. Here, we show that (1) P-ETC and, particularly, water photolysed by photosystem II (PSII) is the source of electrons discharged to the environment by illuminated cyanobacteria, and (2) water-derived electrons are transmitted from PSII to extracellular electron acceptors via plastoquinone and cytochrome bd quinol oxidase. Two cyanobacterial genera (Lyngbya and Nostoc) displayed very similar electrogenic responses when treated with P-ETC site-specific inhibitors, suggesting a conserved electrogenic pathway. We propose that in cyanobacteria, electrogenic activity may represent a form of overflow metabolism to protect cells under high-intensity light. This study offers insight into electron transfer between phototrophic microorganisms and the environment and expands our knowledge into biologically based mechanisms for harnessing solar energy.
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Affiliation(s)
- John M Pisciotta
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, 725 W. Lombard St, Baltimore, MD 21201, USA
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21
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McDonald AE, Ivanov AG, Bode R, Maxwell DP, Rodermel SR, Hüner NPA. Flexibility in photosynthetic electron transport: the physiological role of plastoquinol terminal oxidase (PTOX). BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1807:954-67. [PMID: 21056542 DOI: 10.1016/j.bbabio.2010.10.024] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Revised: 10/27/2010] [Accepted: 10/29/2010] [Indexed: 11/27/2022]
Abstract
Oxygenic photosynthesis depends on a highly conserved electron transport system, which must be particularly dynamic in its response to environmental and physiological changes, in order to avoid an excess of excitation energy and subsequent oxidative damage. Apart from cyclic electron flow around PSII and around PSI, several alternative electron transport pathways exist including a plastoquinol terminal oxidase (PTOX) that mediates electron flow from plastoquinol to O(2). The existence of PTOX was first hypothesized in 1982 and this was verified years later based on the discovery of a non-heme, di-iron carboxylate protein localized to thylakoid membranes that displayed sequence similarity to the mitochondrial alternative oxidase. The absence of this protein renders higher plants susceptible to excitation pressure dependant variegation combined with impaired carotenoid synthesis. Chloroplasts, as well as other plastids (i.e. etioplasts, amyloplasts and chromoplasts), fail to assemble organized internal membrane structures correctly, when exposed to high excitation pressure early in development. While the role of PTOX in plastid development is established, its physiological role under stress conditions remains equivocal and we postulate that it serves as an alternative electron sink under conditions where the acceptor side of PSI is limited. The aim of this review is to provide an overview of the past achievements in this field and to offer directions for future investigative efforts. Plastoquinol terminal oxidase (PTOX) is involved in an alternative electron transport pathway that mediates electron flow from plastoquinol to O(2). This article is part of a Special Issue entitled: Regulation of Electron Transport in Chloroplasts.
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Affiliation(s)
- Allison E McDonald
- Department of Biology, Wilfrid Laurier University, Science Building, 75 University Avenue West, Waterloo, Ontario, Canada N2L 3C5.
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Pisciotta JM, Zou Y, Baskakov IV. Light-dependent electrogenic activity of cyanobacteria. PLoS One 2010; 5:e10821. [PMID: 20520829 PMCID: PMC2876029 DOI: 10.1371/journal.pone.0010821] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2009] [Accepted: 04/22/2010] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Cyanobacteria account for 20-30% of Earth's primary photosynthetic productivity and convert solar energy into biomass-stored chemical energy at the rate of approximately 450 TW [1]. These single-cell microorganisms are resilient predecessors of all higher oxygenic phototrophs and can be found in self-sustaining, nitrogen-fixing communities the world over, from Antarctic glaciers to the Sahara desert [2]. METHODOLOGY/PRINCIPAL FINDINGS Here we show that diverse genera of cyanobacteria including biofilm-forming and pelagic strains have a conserved light-dependent electrogenic activity, i.e. the ability to transfer electrons to their surroundings in response to illumination. Naturally-growing biofilm-forming photosynthetic consortia also displayed light-dependent electrogenic activity, demonstrating that this phenomenon is not limited to individual cultures. Treatment with site-specific inhibitors revealed the electrons originate at the photosynthetic electron transfer chain (P-ETC). Moreover, electrogenic activity was observed upon illumination only with blue or red but not green light confirming that P-ETC is the source of electrons. The yield of electrons harvested by extracellular electron acceptor to photons available for photosynthesis ranged from 0.05% to 0.3%, although the efficiency of electron harvesting likely varies depending on terminal electron acceptor. CONCLUSIONS/SIGNIFICANCE The current study illustrates that cyanobacterial electrogenic activity is an important microbiological conduit of solar energy into the biosphere. The mechanism responsible for electrogenic activity in cyanobacteria appears to be fundamentally different from the one exploited in previously discovered electrogenic bacteria, such as Geobacter, where electrons are derived from oxidation of organic compounds and transported via a respiratory electron transfer chain (R-ETC) [3], [4]. The electrogenic pathway of cyanobacteria might be exploited to develop light-sensitive devices or future technologies that convert solar energy into limited amounts of electricity in a self-sustainable, CO(2)-free manner.
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Affiliation(s)
- John M. Pisciotta
- Center for Biomedical Engineering and Technology, University of Maryland, Baltimore, Maryland, United States of America
| | - Yongjin Zou
- Center for Biomedical Engineering and Technology, University of Maryland, Baltimore, Maryland, United States of America
| | - Ilia V. Baskakov
- Center for Biomedical Engineering and Technology, University of Maryland, Baltimore, Maryland, United States of America
- * E-mail:
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Castielli O, De la Cerda B, Navarro JA, Hervás M, De la Rosa MA. Proteomic analyses of the response of cyanobacteria to different stress conditions. FEBS Lett 2009; 583:1753-8. [DOI: 10.1016/j.febslet.2009.03.069] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2009] [Revised: 03/30/2009] [Accepted: 03/31/2009] [Indexed: 12/21/2022]
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Mogi T, Miyoshi H. Properties of cytochrome bd plastoquinol oxidase from the cyanobacterium Synechocystis sp. PCC 6803. J Biochem 2009; 145:395-401. [PMID: 19124292 DOI: 10.1093/jb/mvn179] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In the aerobic respiratory chain of the cyanobacterium Synechocystis sp. PCC 6803, cytochrome c oxidase serves as a major terminal oxidase while cyanide-resistant cytochrome bd serves as an alternative oxidase and evades the over-reduction of the plastoquinone pool under stress conditions. Here we expressed Synechocystis cytochrome bd in Escherichia coli and characterized enzymatic and spectroscopic properties. Cyanobacterial cytochrome bd showed the higher activity with ubiquinols than with decyl-plastoquinol and K(m) values for quinols were 2-fold smaller than those of E. coli cytochrome bd (CydAB). The dioxygen reduction site was resistant to cyanide as in E. coli oxidase while the quinol oxidation site was more sensitive to antimycin A and quinolone inhibitors. Spectroscopic analysis showed the presence of the haem b(595)-d binuclear centre but the sequence analysis indicates that cyanobacterial cytochrome bd is structurally related to cyanide-insensitive oxidase (CioAB), which does not show typical spectral changes upon reduction and ligand binding. Our data indicate that cyanobacterial cytochrome bd has unique enzymatic and structural properties and we hope that our findings will help our understanding the role and properties of CydAB and CioAB quinol oxidases in other bacterial species.
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Affiliation(s)
- Tatsushi Mogi
- Department of Biomedical Chemistry, Graduate School of Medicine, the University of Tokyo, Bunkyo-ku, Tokyo, Japan.
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Bernroitner M, Zamocky M, Pairer M, Furtmüller PG, Peschek GA, Obinger C. Heme-copper oxidases and their electron donors in cyanobacterial respiratory electron transport. Chem Biodivers 2008; 5:1927-1961. [PMID: 18972533 DOI: 10.1002/cbdv.200890180] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Cyanobacteria are the paradigmatic organisms of oxygenic (plant-type) photosynthesis and aerobic respiration. Since there is still an amazing lack of knowledge on the role and mechanism of their respiratory electron transport, we have critically analyzed all fully or partially sequenced genomes for heme-copper oxidases and their (putative) electron donors cytochrome c(6), plastocyanin, and cytochrome c(M). Well-known structure-function relationships of the two branches of heme-copper oxidases, namely cytochrome c (aa(3)-type) oxidase (COX) and quinol (bo-type) oxidase (QOX), formed the base for a critical inspection of genes and ORFs found in cyanobacterial genomes. It is demonstrated that at least one operon encoding subunits I-III of COX is found in all cyanobacteria, whereas many non-N(2)-fixing species lack QOX. Sequence analysis suggests that both cyanobacterial terminal oxidases should be capable of both the four-electron reduction of dioxygen and proton pumping. All diazotrophic organisms have at least one operon that encodes QOX. In addition, the highly refined specialization in heterocyst forming Nostocales is reflected by the presence of two paralogs encoding COX. The majority of cyanobacterial genomes contain one gene or ORF for plastocyanin and cytochrome c(M), whereas 1-4 paralogs for cytochrome c(6) were found. These findings are discussed with respect to published data about the role of respiration in wild-type and mutated cyanobacterial strains in normal metabolism, stress adaptation, and nitrogen fixation. A model of the branched electron-transport pathways downstream of plastoquinol in cyanobacteria is presented.
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Affiliation(s)
- Margit Bernroitner
- Department of Chemistry, Division of Biochemistry, BOKU-University of Natural Resources and Applied Life Sciences, Muthgasse 18, A-1190 Vienna
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Hart SE, Howe CJ, Mizuguchi K, Fernandez-Recio J. Docking of cytochrome c6 and plastocyanin to the aa3-type cytochrome c oxidase in the cyanobacterium Phormidium laminosum. Protein Eng Des Sel 2008; 21:689-98. [DOI: 10.1093/protein/gzn051] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Bolychevtseva YV, Terekhova IV, Roegner M, Karapetyan NV. Effects of oxygen and photosynthesis carbon cycle reactions on kinetics of P700 redox transients in cyanobacterium Arthrospira platensis cells. BIOCHEMISTRY (MOSCOW) 2007; 72:275-81. [PMID: 17447880 DOI: 10.1134/s0006297907030042] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Effects of oxygen and photosynthesis and respiration inhibitors on the electron transport in photosystem I (PSI) of the cyanobacterium Arthrospira platensis cells were studied. Redox transients of P700 were induced by illumination at 730 nm and monitored as kinetics of the absorption changes at 810 nm; to block electron influx from PSII, the measurements were performed in the presence of 30 microM 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU). Inhibitors of terminal oxidases (potassium cyanide and pentachlorophenol) insignificantly influenced the fast oxidation of P700 under aerobic conditions, whereas removal of oxygen significantly decelerated the accumulation of P700(+). In the absence of oxygen the slow oxidation of P700 observed on the first illumination was accelerated on each subsequent illumination, suggesting an activation of the carbon cycle enzymes. Under the same conditions, pentachlorophenol (an uncoupler) markedly accelerated the P700 photooxidation. Under anaerobic conditions, potassium cyanide (an inhibitor of carbon dioxide assimilation) failed to influence the kinetics of redox transients of P700, whereas iodoacetamide (an inhibitor of NADP(H)-glyceraldehyde-3-phosphate dehydrogenase) completely prevented the photooxidation of P700. Thus, the fast photooxidation of P700 in the A. platensis cells under aerobic conditions in the presence of DCMU was caused by electron transport from PSI onto oxygen, and complicated transient changes in the P700 photooxidation kinetics under anaerobic conditions (in the presence of DCMU) were due to involvement of NADP+ generated during the reducing phase of the carbon cycle.
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Affiliation(s)
- Yu V Bolychevtseva
- Bach Institute of Biochemistry, Russian Academy of Sciences, Moscow, 119071, Russia.
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Sakurai H, Masukawa H. Promoting R & D in photobiological hydrogen production utilizing mariculture-raised cyanobacteria. MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2007; 9:128-45. [PMID: 17340220 DOI: 10.1007/s10126-006-6073-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2006] [Accepted: 08/25/2006] [Indexed: 05/14/2023]
Abstract
This review article explores the potential of using mariculture-raised cyanobacteria as solar energy converters of hydrogen (H(2)). The exploitation of the sea surface for large-scale renewable energy production and the reasons for selecting the economical, nitrogenase-based systems of cyanobacteria for H(2) production, are described in terms of societal benefits. Reports of cyanobacterial photobiological H(2) production are summarized with respect to specific activity, efficiency of solar energy conversion, and maximum H(2) concentration attainable. The need for further improvements in biological parameters such as low-light saturation properties, sustainability of H(2) production, and so forth, and the means to overcome these difficulties through the identification of promising wild-type strains followed by optimization of the selected strains using genetic engineering are also discussed. Finally, a possible mechanism for the development of economical large-scale mariculture operations in conjunction with international cooperation and social acceptance is outlined.
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Affiliation(s)
- Hidehiro Sakurai
- Department of Biology, School of Education, and Major in Bioscience and Biomedical Engineering, Graduate School of Science and Engineering, Waseda University, Nishiwaseda 1, Shinjuku, Tokyo, 169-8050, Japan.
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Abstract
The sequence of the phylogenetic events that preceded the appearance of aldosterone in vertebrates is described, starting from the ancestral conversion of cytochrome P450s from oxygen detoxification to xenobiotic detoxification and synthesis of oxygenated endobiotics with useful functions in intercellular signalling, such as steroid hormones. At the end of the Silurian period [438-408 million yr ago, (Mya)], a complete set of cytochrome P450s for corticoid synthesis was presumably already available, except for mitochondrial cytochrome P450c18 or aldosterone synthase encoded by CYP11B2. This gene arose by duplication of the CYP11B gene in the sarcopterygian or lobe-finned fish/tetrapod line after its divergence from the actinopterygian or ray-finned fish line 420 Mya, but before the beginning of the colonization of land by tetrapods in the late Devonian period, around 370 Mya. The fact that aldosterone is already present in Dipnoi, which occupy an evolutionary transition between water- and air-breathing but are fully aquatic, suggests that the role of this steroid was to potentiate the corticoid response to hypoxia, rather than to prevent dehydration out of the water. In terrestrial amphibians, there is no differentiation between the secretion rates and gluco- and mineralocorticoid effects of aldosterone and corticosterone. In sauropsids, plasma aldosterone concentrations are much lower than in amphibians, but regulation of salt/water balance is dependent upon both aldosterone and corticosterone, though sometimes with opposed actions. In terrestrial mammals, aldosterone acquires a specific mineralocorticoid function, because its interaction with the mineralocorticoid receptor is protected by the coexpression of the enzyme 11beta-hydroxysteroid dehydrogenase type 2, which inactivates both cortisol and corticosterone. There is evidence that aldosterone can be also synthesized extra-adrenally in brain neurons and cardiac myocytes, which lack this protection and where the effects of aldosterone oppose those of glucocorticoids. In conclusion, the phylogenetic history of aldosterone documents the erratic progression of evolutionary changes in the course of the strenuous struggle for environmental resources and survival.
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Affiliation(s)
- L Colombo
- Department of Biology, University of Padua, 35121 Padua, Italy.
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Navarro JA, Durán RV, De la Rosa MA, Hervás M. Respiratory cytochromecoxidase can be efficiently reduced by the photosynthetic redox proteins cytochromec6and plastocyanin in cyanobacteria. FEBS Lett 2005; 579:3565-8. [PMID: 15963511 DOI: 10.1016/j.febslet.2005.05.034] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2005] [Revised: 05/23/2005] [Accepted: 05/23/2005] [Indexed: 11/23/2022]
Abstract
Plastocyanin and cytochrome c6 are two small soluble electron carriers located in the intrathylacoidal space of cyanobacteria. Although their role as electron shuttle between the cytochrome b6f and photosystem I complexes in the photosynthetic pathway is well established, their participation in the respiratory electron transport chain as donors to the terminal oxidase is still under debate. Here, we present the first time-resolved analysis showing that both cytochrome c6 and plastocyanin can be efficiently oxidized by the aa3 type cytochrome c oxidase in Nostoc sp. PCC 7119. The apparent electron transfer rate constants are ca. 250 and 300 s(-1) for cytochrome c6 and plastocyanin, respectively. These constants are 10 times higher than those obtained for the oxidation of horse cytochrome c by the oxidase, in spite of being a reaction thermodynamically more favourable.
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Affiliation(s)
- José A Navarro
- Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla y CSIC, Centro Isla de la Cartuja, Américo Vespucio 49, E-41092 Sevilla, Spain
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