scholarly journals Cyanobakterien als Biokatalysatoren

BIOspektrum ◽  
2021 ◽  
Vol 27 (2) ◽  
pp. 208-210
Author(s):  
Marc M. Nowaczyk ◽  
Hanna C. Grimm ◽  
Leen Assil-Companioni ◽  
Robert Kourist
Keyword(s):  
Natural Process ◽  
Oxygenic Photosynthesis ◽  
Phototrophic Microorganisms ◽  
Electron Sink ◽  
Pcc 6803

AbstractThe highly optimized natural process of oxygenic photosynthesis leads to the formation of redox equivalents, such as NADPH, that can be used to fuel heterologous biotransformations in phototrophic microorganisms. We investigated the reduction of 2-methylmaleimide by the ene-reductase YqjM in the cyanobacterium Synechocystis sp. PCC 6803 and doubled the productivity of the cells by inactivating flavodiironproteins (FDPs) as competing electron sink under self-shading conditions, reaching 18.3 mmol h−1 L−1.

scholarly journals Deletion ofsll1541inSynechocystissp. Strain PCC 6803 Allows Formation of a Far-Red-Shiftedholo-ProteorhodopsinIn Vivo

2018 ◽  
Vol 84 (9) ◽  
Author(s):  
Que Chen ◽  
Jeroen B. van der Steen ◽  
Jos C. Arents ◽  
Aloysius F. Hartog ◽  
Srividya Ganapathy ◽  
...  
Keyword(s):  
Proton Pump ◽  
Essential Gene ◽  
Critical Role ◽  
Action Spectrum ◽  
Atp Synthesis ◽  
Chemical Oxidation ◽  
Oxygenic Photosynthesis ◽  
Content Type ◽  
Pcc 6803

ABSTRACTIn many pro- and eukaryotes, a retinal-based proton pump equips the cell to drive ATP synthesis with (sun)light. Such pumps, therefore, have been proposed as a plug-in for cyanobacteria to artificially increase the efficiency of oxygenic photosynthesis. However, little information on the metabolism of retinal, their chromophore, is available for these organisms. We have studied thein vivoroles of five genes (sll1541,slr1648,slr0091,slr1192, andslr0574) potentially involved in retinal metabolism inSynechocystissp. strain PCC 6803. With a gene deletion approach, we have shown thatSynechocystis apo-carotenoid-15,15-oxygenase (SynACO), encoded by genesll1541, is an indispensable enzyme for retinal synthesis inSynechocystis, presumably via asymmetric cleavage of β-apo-carotenal. The second carotenoid oxygenase (SynDiox2), encoded by geneslr1648, competes with SynACO for substrate(s) but only measurably contributes to retinal biosynthesis in stationary phase via an as-yet-unknown mechanism.In vivodegradation of retinal may proceed through spontaneous chemical oxidation and via enzyme-catalyzed processes. Deletion of geneslr0574(encoding CYP120A1), but not ofslr0091or ofslr1192, causes an increase (relative to the level in wild-typeSynechocystis) in the retinal content in both the linear and stationary growth phases. These results suggest that CYP120A1 does contribute to retinal degradation. Preliminary data obtained using13C-labeled retinal suggest that conversion to retinol and retinoic acid and subsequent further oxidation also play a role. Deletion ofsll1541leads to deficiency in retinal synthesis and allows thein vivoreconstitution of far-red-absorbingholo-proteorhodopsin with exogenous retinal analogues, as demonstrated here for all-trans3,4-dehydroretinal and 3-methylamino-16-nor-1,2,3,4-didehydroretinal.IMPORTANCERetinal is formed by many cyanobacteria and has a critical role in most forms of life for processes such as photoreception, growth, and stress survival. However, the metabolic pathways in cyanobacteria for synthesis and degradation of retinal are poorly understood. In this paper we identify genes involved in its synthesis, characterize their role, and provide an initial characterization of the pathway of its degradation. This led to the identification ofsll1541(encoding SynACO) as the essential gene for retinal synthesis. Multiple pathways for retinal degradation presumably exist. These results have allowed us to construct a strain that expresses a light-dependent proton pump with an action spectrum extending beyond 700 nm. The availability of this strain will be important for further work aimed at increasing the overall efficiency of oxygenic photosynthesis.

scholarly journals Flv1-4 proteins function in versatile combinations in O2 photoreduction in cyanobacteria

2019 ◽  
Author(s):  
Anita Santana-Sánchez ◽  
Daniel Solymosi ◽  
Henna Mustila ◽  
Luca Bersanini ◽  
Eva-Mari Aro ◽  
...  
Keyword(s):  
Steady State ◽  
Life Domains ◽  
Electron Sink ◽  
Pcc 6803

AbstractFlavodiiron proteins (FDPs) constitute a group of modular enzymes widespread in all life Domains. Synechocystis sp. PCC 6803 has four FDPs (Flv1-4) essential for photoprotection of photosynthesis. A direct comparison of the Mehler-like reaction (O2 photoreduction) in high Ci (3% CO2, HC) and low Ci (air level CO2, LC) acclimated cells demonstrated that the Flv1/Flv3 heterodimer is responsible for an efficient steady-state O2 photoreduction under HC, with flv2 and flv4 expression strongly down-regulated. Conversely, under LC conditions Flv1/Flv3 acts only as a transient electron sink due to competing withdrawal of electrons by the highly induced NDH-1 complex. Further, in vivo evidence is provided indicating that Flv2/Flv4 contributes to the Mehler-like reaction when naturally expressed under LC conditions, or when artificially overexpressed under HC. The O2 photoreduction driven by Flv2/Flv4 occurs down-stream of PSI in a coordinated manner with Flv1/Flv3 and supports slow and steady-state O2 photoreduction.

scholarly journals Photosystem II antenna modules CP43 and CP47 do not form a stable ‘no reaction centre complex’ in the cyanobacterium Synechocystis sp. PCC 6803

2022 ◽  
Author(s):  
Martina Bečková ◽  
Roman Sobotka ◽  
Josef Komenda
Keyword(s):  
Photosystem Ii ◽  
High Light ◽  
Oxygenic Photosynthesis ◽  
Reaction Centre ◽  
Wild Type ◽  
Migration Patterns ◽  
Separate Protein ◽  
Antenna Module ◽  
D2 Protein ◽  
Pcc 6803

AbstractThe repair of photosystem II is a key mechanism that keeps the light reactions of oxygenic photosynthesis functional. During this process, the PSII central subunit D1 is replaced with a newly synthesized copy while the neighbouring CP43 antenna with adjacent small subunits (CP43 module) is transiently detached. When the D2 protein is also damaged, it is degraded together with D1 leaving both the CP43 module and the second PSII antenna module CP47 unassembled. In the cyanobacterium Synechocystis sp. PCC 6803, the released CP43 and CP47 modules have been recently suggested to form a so-called no reaction centre complex (NRC). However, the data supporting the presence of NRC can also be interpreted as a co-migration of CP43 and CP47 modules during electrophoresis and ultracentrifugation without forming a mutual complex. To address the existence of NRC, we analysed Synechocystis PSII mutants accumulating one or both unassembled antenna modules as well as Synechocystis wild-type cells stressed with high light. The obtained results were not compatible with the existence of a stable NRC since each unassembled module was present as a separate protein complex with a mutually similar electrophoretic mobility regardless of the presence of the second module. The non-existence of NRC was further supported by isolation of the His-tagged CP43 and CP47 modules from strains lacking either D1 or D2 and their migration patterns on native gels.

scholarly journals Current knowledge and recent advances in understanding metabolism of the model cyanobacterium Synechocystis sp. PCC 6803

2020 ◽  
Vol 40 (4) ◽  
Author(s):  
Lauren A. Mills ◽  
Alistair J. McCormick ◽  
David J. Lea-Smith
Keyword(s):  
Amino Acids ◽  
Heterotrophic Bacteria ◽  
Membrane Lipids ◽  
Current Knowledge ◽  
Oxygenic Photosynthesis ◽  
Photosynthetic Organisms ◽  
Physiological Processes ◽  
Synechocystis Sp ◽  
Pcc 6803

Abstract Cyanobacteria are key organisms in the global ecosystem, useful models for studying metabolic and physiological processes conserved in photosynthetic organisms, and potential renewable platforms for production of chemicals. Characterizing cyanobacterial metabolism and physiology is key to understanding their role in the environment and unlocking their potential for biotechnology applications. Many aspects of cyanobacterial biology differ from heterotrophic bacteria. For example, most cyanobacteria incorporate a series of internal thylakoid membranes where both oxygenic photosynthesis and respiration occur, while CO2 fixation takes place in specialized compartments termed carboxysomes. In this review, we provide a comprehensive summary of our knowledge on cyanobacterial physiology and the pathways in Synechocystis sp. PCC 6803 (Synechocystis) involved in biosynthesis of sugar-based metabolites, amino acids, nucleotides, lipids, cofactors, vitamins, isoprenoids, pigments and cell wall components, in addition to the proteins involved in metabolite transport. While some pathways are conserved between model cyanobacteria, such as Synechocystis, and model heterotrophic bacteria like Escherichia coli, many enzymes and/or pathways involved in the biosynthesis of key metabolites in cyanobacteria have not been completely characterized. These include pathways required for biosynthesis of chorismate and membrane lipids, nucleotides, several amino acids, vitamins and cofactors, and isoprenoids such as plastoquinone, carotenoids, and tocopherols. Moreover, our understanding of photorespiration, lipopolysaccharide assembly and transport, and degradation of lipids, sucrose, most vitamins and amino acids, and haem, is incomplete. We discuss tools that may aid our understanding of cyanobacterial metabolism, notably CyanoSource, a barcoded library of targeted Synechocystis mutants, which will significantly accelerate characterization of individual proteins.

scholarly journals Inactivation of Genes Encoding Plastoglobulin-Like Proteins in Synechocystis sp. PCC 6803 Leads to a Light-Sensitive Phenotype

2010 ◽  
Vol 192 (6) ◽  
pp. 1700-1709 ◽  
Author(s):  
Francis X. Cunningham ◽  
Ashley B. Tice ◽  
Christina Pham ◽  
Elisabeth Gantt
Keyword(s):  
Inclusion Bodies ◽  
Light Stress ◽  
High Irradiance ◽  
Oxygenic Photosynthesis ◽  
Wild Type ◽  
Fundamental Function ◽  
Low Light ◽  
Photooxidative Damage ◽  
Genes Encoding ◽  
Pcc 6803

ABSTRACT Plastoglobulins (PGL) are the predominant proteins of lipid globules in the plastids of flowering plants. Genes encoding proteins similar to plant PGL are also present in algae and cyanobacteria but in no other organisms, suggesting an important role for these proteins in oxygenic photosynthesis. To gain an understanding of the core and fundamental function of PGL, the two genes that encode PGL-like polypeptides in the cyanobacterium Synechocystis sp. PCC 6803 (pgl1 and pgl2) were inactivated individually and in combination. The resulting mutants were able to grow under photoautotrophic conditions, dividing at rates that were comparable to that of the wild-type (WT) under low-light (LL) conditions (10 microeinsteins·m−2·s−1) but lower than that of the WT under moderately high-irradiance (HL) conditions (150 microeinsteins·m−2·s−1). Under HL, each Δpgl mutant had less chlorophyll, a lower photosystem I (PSI)/PSII ratio, more carotenoid per unit of chlorophyll, and very much more myxoxanthophyll (a carotenoid symptomatic of high light stress) per unit of chlorophyll than the WT. Large, heterogeneous inclusion bodies were observed in cells of mutants inactivated in pgl2 or both pgl2 and pgl1 under both LL and HL conditions. The mutant inactivated in both pgl genes was especially sensitive to the light environment, with alterations in pigmentation, heterogeneous inclusion bodies, and a lower PSI/PSII ratio than the WT even for cultures grown under LL conditions. The WT cultures grown under HL contained 2- to 3-fold more PGL1 and PGL2 per cell than cultures grown under LL conditions. These and other observations led us to conclude that the PGL-like polypeptides of Synechocystis play similar but not identical roles in some process relevant to the repair of photooxidative damage.

scholarly journals Overexpression of plastid terminal oxidase in Synechocystis sp. PCC 6803 alters cellular redox state

2017 ◽  
Vol 372 (1730) ◽  
pp. 20160379 ◽  
Author(s):  
Kathleen Feilke ◽  
Ghada Ajlani ◽  
Anja Krieger-Liszkay
Keyword(s):  
Higher Plants ◽  
Photosynthetic Apparatus ◽  
Oxygenic Photosynthesis ◽  
Terminal Oxidase ◽  
Cellular Redox ◽  
Excess Electrons ◽  
Plastid Terminal Oxidase ◽  
Absorption Measurements ◽  
Pcc 6803

Cyanobacteria are the most ancient organisms performing oxygenic photosynthesis, and they are the ancestors of plant plastids. All plastids contain the plastid terminal oxidase (PTOX), while only certain cyanobacteria contain PTOX. Many putative functions have been discussed for PTOX in higher plants including a photoprotective role during abiotic stresses like high light, salinity and extreme temperatures. Since PTOX oxidizes PQH 2 and reduces oxygen to water, it is thought to protect against photo-oxidative damage by removing excess electrons from the plastoquinone (PQ) pool. To investigate the role of PTOX we overexpressed rice PTOX fused to the maltose-binding protein (MBP-OsPTOX) in Synechocystis sp. PCC 6803, a model cyanobacterium that does not encode PTOX. The fusion was highly expressed and OsPTOX was active, as shown by chlorophyll fluorescence and P 700 absorption measurements. The presence of PTOX led to a highly oxidized state of the NAD(P)H/NAD(P) + pool, as detected by NAD(P)H fluorescence. Moreover, in the PTOX overexpressor the electron transport capacity of PSI relative to PSII was higher, indicating an alteration of the photosystem I (PSI) to photosystem II (PSII) stoichiometry. We suggest that PTOX controls the expression of responsive genes of the photosynthetic apparatus in a different way from the PQ/PQH 2 ratio. This article is part of the themed issue ‘Enhancing photosynthesis in crop plants: targets for improvement’.

scholarly journals The Photosystem II Assembly Factor Ycf48 from the Cyanobacterium Synechocystis sp. PCC 6803 Is Lipidated Using an Atypical Lipobox Sequence

2021 ◽  
Vol 22 (7) ◽  
pp. 3733
Author(s):  
Jana Knoppová ◽  
Jianfeng Yu ◽  
Jan Janouškovec ◽  
Petr Halada ◽  
Peter J. Nixon ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Protein Complexes ◽  
Cysteine Residue ◽  
Site Directed Mutagenesis ◽  
Oxygenic Photosynthesis ◽  
Spectrometric Analysis ◽  
C Terminus ◽  
Assembly Factor ◽  
Synechocystis Sp ◽  
Pcc 6803

Photochemical energy conversion during oxygenic photosynthesis is performed by membrane-embedded chlorophyll-binding protein complexes. The biogenesis and maintenance of these complexes requires auxiliary protein factors that optimize the assembly process and protect nascent complexes from photodamage. In cyanobacteria, several lipoproteins contribute to the biogenesis and function of the photosystem II (PSII) complex. They include CyanoP, CyanoQ, and Psb27, which are all attached to the lumenal side of PSII complexes. Here, we show that the lumenal Ycf48 assembly factor found in the cyanobacterium Synechocystis sp. PCC 6803 is also a lipoprotein. Detailed mass spectrometric analysis of the isolated protein supported by site-directed mutagenesis experiments indicates lipidation of the N-terminal C29 residue of Ycf48 and removal of three amino acids from the C-terminus. The lipobox sequence in Ycf48 contains a cysteine residue at the −3 position compared to Leu/Val/Ile residues found in the canonical lipobox sequence. The atypical Ycf48 lipobox sequence is present in most cyanobacteria but is absent in eukaryotes. A possible role for lipoproteins in the coordinated assembly of cyanobacterial PSII is discussed.

scholarly journals A Comprehensive Analysis of the Peroxiredoxin Reduction System in the Cyanobacterium Synechocystis sp. Strain PCC 6803 Reveals that All Five Peroxiredoxins Are Thioredoxin Dependent

2009 ◽  
Vol 191 (24) ◽  
pp. 7477-7489 ◽  
Author(s):  
María Esther Pérez-Pérez ◽  
Alejandro Mata-Cabana ◽  
Ana María Sánchez-Riego ◽  
Marika Lindahl ◽  
Francisco J. Florencio
Keyword(s):  
Hydrogen Peroxide ◽  
Continuous Production ◽  
Expression Patterns ◽  
Catalytic Efficiency ◽  
Growth Conditions ◽  
Electron Donors ◽  
Oxygenic Photosynthesis ◽  
Oxygen Species ◽  
Alkyl Hydroperoxides ◽  
Pcc 6803

ABSTRACT Cyanobacteria perform oxygenic photosynthesis, which gives rise to the continuous production of reactive oxygen species, such as superoxide anion radicals and hydrogen peroxide, particularly under unfavorable growth conditions. Peroxiredoxins, which are present in both chloroplasts and cyanobacteria, constitute a class of thiol-dependent peroxidases capable of reducing hydrogen peroxide as well as alkyl hydroperoxides. Chloroplast peroxiredoxins have been studied extensively and have been found to use a variety of endogenous electron donors, such as thioredoxins, glutaredoxins, or cyclophilin, to sustain their activities. To date, however, the endogenous reduction systems for cyanobacterial peroxiredoxins have not been systematically studied. We have expressed and purified all five Synechocystis sp. strain PCC 6803 peroxiredoxins, which belong to the classes 1-Cys Prx, 2-Cys Prx, type II Prx (PrxII), and Prx Q, and we have examined their capacities to interact with and receive electrons from the m-, x-, and y-type thioredoxins from the same organism, which are called TrxA, TrxB, and TrxQ, respectively. Assays for peroxidase activity demonstrated that all five enzymes could use thioredoxins as electron donors, whereas glutathione and Synechocystis sp. strain PCC 6803 glutaredoxins were inefficient. The highest catalytic efficiency was obtained for the couple consisting of PrxII and TrxQ thioredoxin. Studies of transcript levels for the peroxiredoxins and thioredoxins under different stress conditions highlighted the similarity between the PrxII and TrxQ thioredoxin expression patterns.

scholarly journals Hydrogen production through oxygenic photosynthesis using the cyanobacterium Synechocystis sp. PCC 6803 in a bio-photoelectrolysis cell (BPE) system

2013 ◽  
Vol 6 (9) ◽  
pp. 2682 ◽  
Author(s):  
Alistair J. McCormick ◽  
Paolo Bombelli ◽  
David J. Lea-Smith ◽  
Robert W. Bradley ◽  
Amanda M. Scott ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Oxygenic Photosynthesis ◽  
Synechocystis Sp ◽  
Pcc 6803
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