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Wilkening S, Schmitt FJ, Lenz O, Zebger I, Horch M, Friedrich T. Discriminating changes in intracellular NADH/NAD + levels due to anoxicity and H 2 supply in R. eutropha cells using the Frex fluorescence sensor. Biochim Biophys Acta Bioenerg 2019; 1860:148062. [PMID: 31419395 DOI: 10.1016/j.bbabio.2019.148062] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 07/23/2019] [Accepted: 08/10/2019] [Indexed: 12/19/2022]
Abstract
The hydrogen-oxidizing "Knallgas" bacterium Ralstonia eutropha can thrive in aerobic and anaerobic environments and readily switches between heterotrophic and autotrophic metabolism, making it an attractive host for biotechnological applications including the sustainable H2-driven production of hydrocarbons. The soluble hydrogenase (SH), one out of four different [NiFe]-hydrogenases in R. eutropha, mediates H2 oxidation even in the presence of O2, thus providing an ideal model system for biological hydrogen production and utilization. The SH reversibly couples H2 oxidation with the reduction of NAD+ to NADH, thereby enabling the sustainable regeneration of this biotechnologically important nicotinamide cofactor. Thus, understanding the interaction of the SH with the cellular NADH/NAD+ pool is of high interest. Here, we applied the fluorescent biosensor Frex to measure changes in cytoplasmic [NADH] in R. eutropha cells under different gas supply conditions. The results show that Frex is well-suited to distinguish SH-mediated changes in the cytoplasmic redox status from effects of general anaerobiosis of the respiratory chain. Upon H2 supply, the Frex reporter reveals a robust fluorescence response and allows for monitoring rapid changes in cellular [NADH]. Compared to the Peredox fluorescence reporter, Frex displays a diminished NADH affinity, which prevents the saturation of the sensor under typical bacterial [NADH] levels. Thus, Frex is a valuable reporter for on-line monitoring of the [NADH]/[NAD+] redox state in living cells of R. eutropha and other proteobacteria. Based on these results, strategies for a rational optimization of fluorescent NADH sensors are discussed.
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Affiliation(s)
- S Wilkening
- Technische Universität Berlin, Institut für Chemie PC 14, Straße des 17. Juni 135, 10623 Berlin, Germany
| | - F-J Schmitt
- Technische Universität Berlin, Institut für Chemie PC 14, Straße des 17. Juni 135, 10623 Berlin, Germany
| | - O Lenz
- Technische Universität Berlin, Institut für Chemie PC 14, Straße des 17. Juni 135, 10623 Berlin, Germany
| | - I Zebger
- Technische Universität Berlin, Institut für Chemie PC 14, Straße des 17. Juni 135, 10623 Berlin, Germany
| | - M Horch
- Technische Universität Berlin, Institut für Chemie PC 14, Straße des 17. Juni 135, 10623 Berlin, Germany; Department of Chemistry and York Biomedical Research Institute, University of York, YO10 5DD, United Kingdom
| | - T Friedrich
- Technische Universität Berlin, Institut für Chemie PC 14, Straße des 17. Juni 135, 10623 Berlin, Germany.
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Katz S, Noth J, Horch M, Shafaat HS, Happe T, Hildebrandt P, Zebger I. Vibrational spectroscopy reveals the initial steps of biological hydrogen evolution. Chem Sci 2016; 7:6746-6752. [PMID: 28451119 PMCID: PMC5355867 DOI: 10.1039/c6sc01098a] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 06/29/2016] [Indexed: 12/30/2022] Open
Abstract
[FeFe] hydrogenases are biocatalytic model systems for the exploitation and investigation of catalytic hydrogen evolution. Here, we used vibrational spectroscopic techniques to characterize, in detail, redox transformations of the [FeFe] and [4Fe4S] sub-sites of the catalytic centre (H-cluster) in a monomeric [FeFe] hydrogenase. Through the application of low-temperature resonance Raman spectroscopy, we discovered a novel metastable intermediate that is characterized by an oxidized [FeIFeII] centre and a reduced [4Fe4S]1+ cluster. Based on this unusual configuration, this species is assigned to the first, deprotonated H-cluster intermediate of the [FeFe] hydrogenase catalytic cycle. Providing insights into the sequence of initial reaction steps, the identification of this species represents a key finding towards the mechanistic understanding of biological hydrogen evolution.
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Affiliation(s)
- S Katz
- Institut für Chemie , Technische Universitaet Berlin , Strasse des 17. Juni 135 , D-10623 Berlin , Germany . ;
| | - J Noth
- Fakultaet für Biologie und Biotechnologie , Lehrstuhl für Biochemie der Pflanzen , AG Photobiotechnologie , Ruhr-Universitaet Bochum , Universitaetsstrasse 150 , D-44801 Bochum , Germany
| | - M Horch
- Institut für Chemie , Technische Universitaet Berlin , Strasse des 17. Juni 135 , D-10623 Berlin , Germany . ;
| | - H S Shafaat
- Max-Planck-Institut für Chemische Energiekonversion , Stiftstraße 34-36 , D-45470 , Muelheim an der Ruhr , Germany
| | - T Happe
- Fakultaet für Biologie und Biotechnologie , Lehrstuhl für Biochemie der Pflanzen , AG Photobiotechnologie , Ruhr-Universitaet Bochum , Universitaetsstrasse 150 , D-44801 Bochum , Germany
| | - P Hildebrandt
- Institut für Chemie , Technische Universitaet Berlin , Strasse des 17. Juni 135 , D-10623 Berlin , Germany . ;
| | - I Zebger
- Institut für Chemie , Technische Universitaet Berlin , Strasse des 17. Juni 135 , D-10623 Berlin , Germany . ;
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Ly HK, Wrzolek P, Heidary N, Götz R, Horch M, Kozuch J, Schwalbe M, Weidinger IM. 2 nd coordination sphere controlled electron transfer of iron hangman complexes on electrodes probed by surface enhanced vibrational spectroscopy. Chem Sci 2015; 6:6999-7007. [PMID: 29861938 PMCID: PMC5947519 DOI: 10.1039/c5sc02560e] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 09/04/2015] [Indexed: 12/14/2022] Open
Abstract
Surface enhanced vibrational spectroscopy shows the correlation between electron transfer kinetics and protonation degree of Fe Hangman complexes on electrodes.
Iron hangman complexes exhibit improved catalytic properties regarding O2 and H2O2 reduction, which are attributed to the presence of a proton donating group in defined vicinity of the catalytic metal centre. Surface enhanced resonance Raman (SERR) and IR (SEIRA) spectro-electrochemistry has been applied concomitantly for the first time to analyse such iron hangman porphyrin complexes attached to electrodes in aqueous solution. While the SERR spectra yield information about the redox state of the central iron, the SEIRA spectra show protonation and deprotonation events of the 2nd coordination sphere. To investigate the influence of a proton active hanging group on the heterogeneous electron transfer between the iron porphyrin and the electrode, two hangman complexes with either an acid or ester functional group were compared. Using time resolved SERR spectroscopy the electron transfer rates of both complexes were determined. Complexes with an acid group showed a slow electron transfer rate at neutral pH that increased significantly at pH 4, while complexes with an ester group exhibited a much faster, but pH independent rate. SEIRA measurements were able to determine directly for the first time a pKa value of 3.4 of a carboxylic hanging group in the immobilized state that shifted to 5.2 in D2O buffer solution. The kinetic data showed an increase of the heterogeneous electron transfer rate with the protonation degree of the acid groups. From these results, we propose a PCET which is strongly modulated by the protonation state of the acid hanging group via hydrogen bond interactions.
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Affiliation(s)
- H K Ly
- Department of Chemistry , Technische Universität Berlin , PC14, Straße des 17. Juni 135 , D-10623 Berlin , Germany . ;
| | - P Wrzolek
- Department of Chemistry , Humboldt Universität zu Berlin , Brook-Taylor-Str. 2 , D-12489 Berlin , Germany .
| | - N Heidary
- Department of Chemistry , Technische Universität Berlin , PC14, Straße des 17. Juni 135 , D-10623 Berlin , Germany . ;
| | - R Götz
- Department of Chemistry , Technische Universität Berlin , PC14, Straße des 17. Juni 135 , D-10623 Berlin , Germany . ;
| | - M Horch
- Department of Chemistry , Technische Universität Berlin , PC14, Straße des 17. Juni 135 , D-10623 Berlin , Germany . ;
| | - J Kozuch
- Department of Chemistry , Technische Universität Berlin , PC14, Straße des 17. Juni 135 , D-10623 Berlin , Germany . ;
| | - M Schwalbe
- Department of Chemistry , Humboldt Universität zu Berlin , Brook-Taylor-Str. 2 , D-12489 Berlin , Germany .
| | - I M Weidinger
- Department of Chemistry , Technische Universität Berlin , PC14, Straße des 17. Juni 135 , D-10623 Berlin , Germany . ;
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Abstract
Challenges and chances in bio-molecular spectroscopy are exemplified by vibrational case studies on metalloenzymes.
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Affiliation(s)
- M. Horch
- Technische Universität Berlin
- Institut für Chemie
- D-10623 Berlin
- Germany
| | - P. Hildebrandt
- Technische Universität Berlin
- Institut für Chemie
- D-10623 Berlin
- Germany
| | - I. Zebger
- Technische Universität Berlin
- Institut für Chemie
- D-10623 Berlin
- Germany
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Horch M, Pinto AF, Utesch T, Mroginski MA, Romão CV, Teixeira M, Hildebrandt P, Zebger I. Reductive activation and structural rearrangement in superoxide reductase: a combined infrared spectroscopic and computational study. Phys Chem Chem Phys 2014; 16:14220-30. [DOI: 10.1039/c4cp00884g] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Local and global structural changes that enable reductive activation of superoxide reductase are revealed by a combined approach of infrared difference spectroscopy and computational methods.
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Affiliation(s)
- M. Horch
- Technische Universität Berlin
- Institut für Chemie
- 10623 Berlin, Germany
| | - A. F. Pinto
- Instituto de Tecnologia Química e Biológica António Xavier
- Universidade Nova de Lisboa
- Av. da República (EAN)
- P-2780-157 Oeiras, Portugal
| | - T. Utesch
- Technische Universität Berlin
- Institut für Chemie
- 10623 Berlin, Germany
| | - M. A. Mroginski
- Technische Universität Berlin
- Institut für Chemie
- 10623 Berlin, Germany
| | - C. V. Romão
- Instituto de Tecnologia Química e Biológica António Xavier
- Universidade Nova de Lisboa
- Av. da República (EAN)
- P-2780-157 Oeiras, Portugal
| | - M. Teixeira
- Instituto de Tecnologia Química e Biológica António Xavier
- Universidade Nova de Lisboa
- Av. da República (EAN)
- P-2780-157 Oeiras, Portugal
| | - P. Hildebrandt
- Technische Universität Berlin
- Institut für Chemie
- 10623 Berlin, Germany
| | - I. Zebger
- Technische Universität Berlin
- Institut für Chemie
- 10623 Berlin, Germany
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Horch M, Lauterbach L, Lenz O, Hildebrandt P, Zebger I. NAD(H)-coupled hydrogen cycling - structure-function relationships of bidirectional [NiFe] hydrogenases. FEBS Lett 2011; 586:545-56. [PMID: 22056977 DOI: 10.1016/j.febslet.2011.10.010] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 10/05/2011] [Accepted: 10/06/2011] [Indexed: 10/15/2022]
Abstract
Hydrogenases catalyze the activation or production of molecular hydrogen. Due to their potential importance for future biotechnological applications, these enzymes have been in the focus of intense research for the past decades. Bidirectional [NiFe] hydrogenases are of particular interest as they couple the reversible cleavage of hydrogen to the redox conversion of NAD(H). In this account, we review the current state of knowledge about mechanistic aspects and structural determinants of these complex multi-cofactor enzymes. Special emphasis is laid on the oxygen-tolerant NAD(H)-linked bidirectional [NiFe] hydrogenase from Ralstonia eutropha.
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Affiliation(s)
- M Horch
- Technische Universität Berlin, Institut für Chemie, Sekr. PC 14, Straße des 17. Juni 135, D-10623 Berlin, Germany
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