Elektronenbifurkierende Enzyme im Energiestoffwechsel des acetogenen Modelorganismus Acetobacterium woodii
Zusammenfassung der Projektergebnisse
Electron bifurcation is a fundamental energy saving process discovered rather recently to be of vital importance in anaerobic bacteria and archaea. An endergonic redox reaction is not driven by ATP hydrolysis or coupling to an ion-motive force across the cytoplasmic membrane but in a soluble protein by coupling to a simultaneous exergonic redox reaction. Thus, cellular energy in the form of ATP or the transmembrane electrochemical ion gradient is saved which is of special importance for anaerobic microorganisms that, in general, have a very low ATP/substrate ratio or that even live at the thermodynamic edge of life. The study of the function of electron-bifurcating enzymes is a very active field in microbiology and biochemistry and pursued by many groups internationally. We have concentrated on electron-bifurcating enzymes that we discovered in the first and the second funding period. Alltogether, we were very successful with eight publications, three more are in the pipeline. We discovered a novel electron-bifurcating transhydrogenase (Stn) in Sporomusa ovata that is widespread in the anaerobic world. We also purified and characterized an electron-bifurcating formate dehydrogenase-hydrogenase complex from S. ovata (not yet published). Together with the group of Dr. Jan Schuller, Marburg, and Dr. U. Ermler, Frankfurt, we solved the high-resolution structures of several of the electron-bifurcating enzymes: the FeFe-hydrogenase, the Stn transhydrogenase, the lactate dehydrogenase and the formate dehydrogenase/hydrogenase complex. We also postulated a novel reaction mechanism for electon-bifurcation in enzymes that do not use the mechanism of flavin-based electron bifurcation (FBEB). With high resolution structures obtained from different enzmyes we also delved into the modularity and exchange of modules in different electron-bifurcating enzymes. Since we discovered novel electron-bifurcating enzymes and since the structure determinations were so successful, but required extensive sitedirected mutagenesis experiments, we did not find time to work further on the caffeyl-CoA reductase as originally planned. I would like to emphasize that the genetic systems that we developed for A. woodii and T. kivui allowed us to probe electron transfer pathways and reaction mechanisms derived from the structural data by site-directed mutagenesis experiments in vitro and in vivo.
Projektbezogene Publikationen (Auswahl)
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The Sporomusa type Nfn is a novel type of electron-bifurcating transhydrogenase that links the redox pools in acetogenic bacteria. Scientific Reports, 10(1).
Kremp, Florian; Roth, Jennifer & Müller, Volker
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Biochemistry of methanol‐dependent acetogenesis in Eubacterium callanderi KIST612. Environmental Microbiology, 23(8), 4505-4517.
Dietrich, Helge M.; Kremp, Florian; Öppinger, Christian; Ribaric, Luna & Müller, Volker
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Electron carriers involved in autotrophic and heterotrophic acetogenesis in the thermophilic bacterium Thermoanaerobacter kivui. Extremophiles, 25(5-6), 513-526.
Katsyv, Alexander; Jain, Surbhi; Basen, Mirko & Müller, Volker
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Energy Conservation in the Acetogenic Bacterium Clostridium aceticum. Microorganisms, 9(2), 258.
Wiechmann, Anja & Müller, Volker
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Structure-based electron-confurcation mechanism of the Ldh-EtfAB complex. eLife, 11.
Kayastha, Kanwal; Katsyv, Alexander; Himmrich, Christina; Welsch, Sonja; Schuller, Jan M.; Ermler, Ulrich & Müller, Volker
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A novel hexameric NADP+‐reducing [FeFe] hydrogenase from Moorella thermoacetica. The FEBS Journal, 291(3), 596-608.
Rosenbaum, Florian P. & Müller, Volker
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Molecular architecture and electron transfer pathway of the Stn family transhydrogenase. Nature Communications, 14(1).
Kumar, Anuj; Kremp, Florian; Roth, Jennifer; Freibert, Sven A.; Müller, Volker & Schuller, Jan M.
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Molecular Basis of the Electron Bifurcation Mechanism in the [FeFe]-Hydrogenase Complex HydABC. Journal of the American Chemical Society, 145(10), 5696-5709.
Katsyv, Alexander; Kumar, Anuj; Saura, Patricia; Pöverlein, Maximilian C.; Freibert, Sven A.; T., Stripp Sven; Jain, Surbhi; Gamiz-Hernandez, Ana P.; Kaila, Ville R. I.; Müller, Volker & Schuller, Jan M.
