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Erdem E, Malihan-Yap L, Assil-Companioni L, Grimm H, Barone GD, Serveau-Avesque C, Amouric A, Duquesne K, de Berardinis V, Allahverdiyeva Y, Alphand V, Kourist R. Photobiocatalytic Oxyfunctionalization with High Reaction Rate using a Baeyer-Villiger Monooxygenase from Burkholderia xenovorans in Metabolically Engineered Cyanobacteria. ACS Catal 2022; 12:66-72. [PMID: 35036041 PMCID: PMC8751089 DOI: 10.1021/acscatal.1c04555] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Revised: 12/03/2021] [Indexed: 01/26/2023]
Abstract
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Baeyer–Villiger
monooxygenases (BVMOs) catalyze the oxidation
of ketones to lactones under very mild reaction conditions. This enzymatic
route is hindered by the requirement of a stoichiometric supply of
auxiliary substrates for cofactor recycling and difficulties with
supplying the necessary oxygen. The recombinant production of BVMO
in cyanobacteria allows the substitution of auxiliary organic cosubstrates
with water as an electron donor and the utilization of oxygen generated
by photosynthetic water splitting. Herein, we report the identification
of a BVMO from Burkholderia xenovorans (BVMOXeno) that exhibits higher reaction
rates in comparison to currently identified BVMOs. We report a 10-fold
increase in specific activity in comparison to cyclohexanone monooxygenase
(CHMOAcineto) in Synechocystis sp. PCC 6803 (25 vs 2.3 U gDCW–1 at
an optical density of OD750 = 10) and an initial rate of
3.7 ± 0.2 mM h–1. While the cells containing
CHMOAcineto showed a considerable reduction
of cyclohexanone to cyclohexanol, this unwanted side reaction was
almost completely suppressed for BVMOXeno, which was attributed to the much faster lactone formation and a
10-fold lower KM value of BVMOXeno toward cyclohexanone. Furthermore, the whole-cell
catalyst showed outstanding stereoselectivity. These results show
that, despite the self-shading of the cells, high specific activities
can be obtained at elevated cell densities and even further increased
through manipulation of the photosynthetic electron transport chain
(PETC). The obtained rates of up to 3.7 mM h–1 underline
the usefulness of oxygenic cyanobacteria as a chassis for enzymatic
oxidation reactions. The photosynthetic oxygen evolution can contribute
to alleviating the highly problematic oxygen mass-transfer limitation
of oxygen-dependent enzymatic processes.
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Affiliation(s)
- Elif Erdem
- Institute of Molecular Biotechnology, Graz University of Technology, NAWI Graz, Petersgasse 14, 8010 Graz, Austria.,Aix Marseille Univ, CNRS, Centrale Marseille, iSm2 UMR7313, 13397 Marseille, France
| | - Lenny Malihan-Yap
- Institute of Molecular Biotechnology, Graz University of Technology, NAWI Graz, Petersgasse 14, 8010 Graz, Austria
| | - Leen Assil-Companioni
- Institute of Molecular Biotechnology, Graz University of Technology, NAWI Graz, Petersgasse 14, 8010 Graz, Austria.,ACIB GmbH, 8010 Graz, Austria
| | - Hanna Grimm
- Institute of Molecular Biotechnology, Graz University of Technology, NAWI Graz, Petersgasse 14, 8010 Graz, Austria
| | - Giovanni Davide Barone
- Institute of Molecular Biotechnology, Graz University of Technology, NAWI Graz, Petersgasse 14, 8010 Graz, Austria.,i3S, Instituto de Investigação em Saúde Universidade do Porto & IBMC, Instituto de Biologia Molecular e Celular, R. Alfredo Allen 208, 4200-135 Porto, Portugal.,Departamento de Biologia Faculdade de Ciências, Universidade do Porto Rua do Campo Alegre, Edifício FC4, 4169-007 Porto, Portugal
| | | | - Agnes Amouric
- Aix Marseille Univ, CNRS, Centrale Marseille, iSm2 UMR7313, 13397 Marseille, France
| | - Katia Duquesne
- Aix Marseille Univ, CNRS, Centrale Marseille, iSm2 UMR7313, 13397 Marseille, France
| | - Véronique de Berardinis
- Génomique métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Univ Evry, Université Paris-Saclay, 91057 Evry, France
| | - Yagut Allahverdiyeva
- Molecular Plant Biology Unit, Department of Life Technologies, Faculty of Technology, University of Turku, Turku 20014, Finland
| | - Véronique Alphand
- Aix Marseille Univ, CNRS, Centrale Marseille, iSm2 UMR7313, 13397 Marseille, France
| | - Robert Kourist
- Institute of Molecular Biotechnology, Graz University of Technology, NAWI Graz, Petersgasse 14, 8010 Graz, Austria.,ACIB GmbH, 8010 Graz, Austria
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Electron-transfer kinetics in cyanobacterial cells: methyl viologen is a poor inhibitor of linear electron flow. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1847:212-222. [PMID: 25448535 DOI: 10.1016/j.bbabio.2014.10.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Revised: 10/24/2014] [Accepted: 10/28/2014] [Indexed: 01/13/2023]
Abstract
The inhibitor methyl viologen (MV) has been widely used in photosynthesis to study oxidative stress. Its effects on electron transfer kinetics in Synechocystis sp. PCC6803 cells were studied to characterize its electron-accepting properties. For the first hundreds of flashes following MV addition at submillimolar concentrations, the kinetics of NADPH formation were hardly modified (less than 15% decrease in signal amplitude) with a significant signal decrease only observed after more flashes or continuous illumination. The dependence of the P700 photooxidation kinetics on the MV concentration exhibited a saturation effect at 0.3 mM MV, a concentration which inhibits the recombination reactions in photosystem I. The kinetics of NADPH formation and decay under continuous light with MV at 0.3 mM showed that MV induces the oxidation of the NADP pool in darkness and that the yield of linear electron transfer decreased by only 50% after 1.5-2 photosystem-I turnovers. The unexpectedly poor efficiency of MV in inhibiting NADPH formation was corroborated by in vitro flash-induced absorption experiments with purified photosystem-I, ferredoxin and ferredoxin-NADP(+)-oxidoreductase. These experiments showed that the second-order rate constants of MV reduction are 20 to 40-fold smaller than the competing rate constants involved in reduction of ferredoxin and ferredoxin-NADP(+)-oxidoreductase. The present study shows that MV, which accepts electrons in vivo both at the level of photosystem-I and ferredoxin, can be used at submillimolar concentrations to inhibit recombination reactions in photosystem-I with only a moderate decrease in the efficiency of fast reactions involved in linear electron transfer and possibly cyclic electron transfer.
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Mustila H, Allahverdiyeva Y, Isojärvi J, Aro EM, Eisenhut M. The bacterial-type [4Fe-4S] ferredoxin 7 has a regulatory function under photooxidative stress conditions in the cyanobacterium Synechocystis sp. PCC 6803. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:1293-304. [PMID: 24780314 DOI: 10.1016/j.bbabio.2014.04.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2013] [Revised: 04/10/2014] [Accepted: 04/13/2014] [Indexed: 12/15/2022]
Abstract
Ferredoxins function as electron carrier in a wide range of metabolic and regulatory reactions. It is not clear yet, whether the multiplicity of ferredoxin proteins is also reflected in functional multiplicity in photosynthetic organisms. We addressed the biological function of the bacterial-type ferredoxin, Fed7 in the cyanobacterium Synechocystis sp. PCC 6803. The expression of fed7 is induced under low CO₂ conditions and further enhanced by additional high light treatment. These conditions are considered as promoting photooxidative stress, and prompted us to investigate the biological function of Fed7 under these conditions. Loss of Fed7 did not inhibit growth of the mutant strain Δfed7 but significantly modulated photosynthesis parameters when the mutant was grown under low CO₂ and high light conditions. Characteristics of the Δfed7 mutant included elevated chlorophyll and photosystem I levels as well as reduced abundance and activity of photosystem II. Transcriptional profiling of the mutant under low CO₂ conditions demonstrated changes in gene regulation of the carbon concentrating mechanism and photoprotective mechanisms such as the Flv2/4 electron valve, the PSII dimer stabilizing protein Sll0218, and chlorophyll biosynthesis. We conclude that the function of Fed7 is connected to coping with photooxidative stress, possibly by constituting a redox-responsive regulatory element in photoprotection. In photosynthetic eukaryotes domains homologous to Fed7 are exclusively found in chloroplast DnaJ-like proteins that are likely involved in remodeling of regulator protein complexes. It is conceivable that the regulatory function of Fed7 evolved in cyanobacteria and was recruited by Viridiplantae as the controller for the chloroplast DnaJ-like proteins.
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Affiliation(s)
- H Mustila
- Laboratory of Molecular Plant Biology, Department of Biochemistry, University of Turku, 20014 Turku, Finland.
| | - Y Allahverdiyeva
- Laboratory of Molecular Plant Biology, Department of Biochemistry, University of Turku, 20014 Turku, Finland.
| | - J Isojärvi
- Laboratory of Molecular Plant Biology, Department of Biochemistry, University of Turku, 20014 Turku, Finland.
| | - E M Aro
- Laboratory of Molecular Plant Biology, Department of Biochemistry, University of Turku, 20014 Turku, Finland.
| | - M Eisenhut
- Laboratory of Molecular Plant Biology, Department of Biochemistry, University of Turku, 20014 Turku, Finland.
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Schuergers N, Ruppert U, Watanabe S, Nürnberg DJ, Lochnit G, Dienst D, Mullineaux CW, Wilde A. Binding of the RNA chaperone Hfq to the type IV pilus base is crucial for its function in Synechocystis sp. PCC 6803. Mol Microbiol 2014; 92:840-52. [PMID: 24684190 DOI: 10.1111/mmi.12595] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/26/2014] [Indexed: 12/17/2022]
Abstract
The bacterial RNA-binding protein Hfq functions in post-transcriptional regulation of gene expression. There is evidence in a range of bacteria for specific subcellular localization of Hfq; however, the mechanism and role of Hfq localization remain unclear. Cyanobacteria harbour a subfamily of Hfq that is structurally conserved but exhibits divergent RNA binding sites. Mutational analysis in the cyanobacterium Synechocystis sp. PCC 6803 revealed that several conserved amino acids on the proximal side of the Hfq hexamer are crucial not only for Hfq-dependent RNA accumulation but also for phototaxis, the latter of which depends on type IV pili. Co-immunoprecipitation and yeast two-hybrid analysis show that the secretion ATPase PilB1 (a component of the type IV pilus base) is an interaction partner of Hfq. Fluorescence microscopy revealed that Hfq is localized to the cytoplasmic membrane in a PilB1-dependent manner. Concomitantly, Hfq-dependent RNA accumulation is abrogated in a ΔpilB1 mutant, indicating that localization to the pilus base via interaction with PilB1 is essential for Hfq function in cyanobacteria.
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Affiliation(s)
- Nils Schuergers
- Molekulare Genetik, Fakultät für Biologie, Albert-Ludwigs-Universität Freiburg, Freiburg, D-79104, Germany
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Kauny J, Sétif P. NADPH fluorescence in the cyanobacterium Synechocystis sp. PCC 6803: a versatile probe for in vivo measurements of rates, yields and pools. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:792-801. [PMID: 24463053 DOI: 10.1016/j.bbabio.2014.01.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Revised: 01/10/2014] [Accepted: 01/13/2014] [Indexed: 10/25/2022]
Abstract
We measured the kinetics of light-induced NADPH formation and subsequent dark consumption by monitoring in vivo its fluorescence in the cyanobacterium Synechocystis PCC 6803. Spectral data allowed the signal changes to be attributed to NAD(P)H and signal linearity vs the chlorophyll concentration was shown to be recoverable after appropriate correction. Parameters associated to reduction of NADP(+) to NADPH by ferredoxin-NADP(+)-oxidoreductase were determined: After single excitation of photosystem I, half of the signal rise is observed in 8ms; Evidence for a kinetic limitation which is attributed to an enzyme bottleneck is provided; After two closely separated saturating flashes eliciting two photosystem I turnovers in less than 2ms, more than 50% of the cytoplasmic photoreductants (reduced ferredoxin and photosystem I acceptors) are diverted from NADPH formation by competing processes. Signal quantitation in absolute NADPH concentrations was performed by adding exogenous NADPH to the cell suspensions and by estimating the enhancement factor of in vivo fluorescence (between 2 and 4). The size of the visible (light-dependent) NADP (NADP(+)+NADPH) pool was measured to be between 1.4 and 4 times the photosystem I concentration. A quantitative discrepancy is found between net oxygen evolution and NADPH consumption by the light-activated Calvin-Benson cycle. The present study shows that NADPH fluorescence is an efficient probe for studying in vivo the energetic metabolism of cyanobacteria which can be used for assessing multiple phenomena occurring over different time scales.
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Affiliation(s)
- Jocelyn Kauny
- iBiTec-S, CNRS UMR 8221, CEA Saclay, 91191 Gif-sur-Yvette, France.
| | - Pierre Sétif
- iBiTec-S, CNRS UMR 8221, CEA Saclay, 91191 Gif-sur-Yvette, France.
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