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Wednesday, January 30

Flavin-Based Electron Bifurcation in Anaerobic Bacteria and Archaea:
A Novel Mechanism of Energy Coupling

Rudolf Kurt Thauer, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
Energy and Environmental Sciences Directorate Seminar
10:00 AM — 11:00 AM, Joint Institute for Computatiional Sciences (Building 5100)
Auditorium (Room 128)
Contact: Martin Keller (kellerm@ornl.gov), 865.574.4333

Abstract

Five years ago we discovered that the cytoplasmic butyryl-CoA dehydrogenase-EtfAB complex from Clostridia couples the endergonic reduction of ferredoxin with NADH to the exergonic reduction of crotonyl-CoA to butyryl-CoA with NADH via flavin-based electronbifurcation [1,2]. Since then four other cytoplasmic enzyme complexes were found capable of coupling endergonic to exergonic redox reactions via this novel mechanism in anaerobic bacteria and archaea. These are ferredoxin- and NAD-dependent [FeFe]-hydrogenase from Thermotoga and acetogenic bacteria [3, 6, 8], NADH-dependent reduced ferredoxin: NADP oxidoreductase from Clostridia [4, 7], the MvhADG-HdrABC complex from methanogenic archaea [5], and the ferredoxin-and NADP-dependent [FeFe]-hydrogenase from syngas fermenting acetogenic Clostridia [in preparation]. These findings have revolutionized our understanding of the energy metabolism of strict anaerobes [9].

[1] F. Li, J. Hinderberger, H. Seedorf, J. Zhang, W. Buckel and R. K. Thauer (2008) Coupled ferredoxin and crotonyl coenzyme A (CoA) reduction with NADH catalyzed by the butyryl-CoA dehydrogenasee/Etf complex from Clostridium kluyveri. J. Bacteriol. 190, 843-850.
[2] G. Herrmann, E. Jayamani, G. Mai and W. Buckel W (2008) Energy conservation via electron-transferring flavoprotein in anaerobic bacteria. J. Bacteriol. 190, 784-791.
[3] G. J. Schut and M. W. Adams (2009) The iron-hydrogenase of Thermotoga maritima utilizes ferredoxin and NADH synergistically: a new perspective on anaerobic hydrogen production. J. Bacteriol. 191, 4451-4457.
[4] S. Wang, H. Huang, J. Moll and R. K. Thauer (2010) NADP+ reduction with reduced ferredoxin and NADP+ reduction with NADH are coupled via an electron bifurcating enzyme complex in Clostridium kluyveri. J. Bacteriol. 192, 5115-5123.
[5] A. K. Kaster, J. Moll, K. Parey, and R. K. Thauer (2011) Coupling of ferredoxin- and heterodisulfide reduction with H2 via electron bifurcation in hydrogenotrophic methanogenic archaea. Proc. Natl. Acad. Sci. USA 108, 2981-2986.
[6] K. Schuchmann and V. Müller (2012) A bacterial electron-bifurcating hydrogenase. J. Biol. Chem. 287, 31165-31171.
[7] H. Huang, S. Wang, J. Moll and R. K. Thauer (2012) Electron-bifurcation involved in the energy metabolism of the acetogen bacterium Moorella thermoacetica. J. Bacteriol. 194, 3689-3699.
[8] S. Wang, H. Huang, J. Kahnt and R. K. Thauer (2013) A reversible electron-bifurcating [FeFe]-hydrogenase (HydABC) in Moorella thermoacetica. J. Bacteriol. In press.
[9] W. Buckel and R. K. Thauer (2012) Energy conservation via electron-bifurcating ferredoxin reduction and proton/Na+ translocating ferredoxin oxidation. Biochim. Biophys. Acta doi:10.1016/j.bbabio.2012.07.002.