Prof. Dr. Wolfgang Buckel
Wolfgang Buckel (born 22.11.1940)
Diplom (Chemistry), Universität München, 1965
Dr. rer. nat. (Biochemistry), Universität München, 1968
Akademischer Rat/Direktor, Universität Regensburg, 1969-1987
Postdoc (Microbiology), University of California, Berkeley, 1970-1971
Habilitation (Biochemistry), Universität Regensburg, 1975
Professor of Microbiology at the Philipps-Universität, 1987-2008
Max Planck Fellow of the MPI for Terrestrial Microbiology, since 2008
Dean of the Fachbereich Biologie, Philipps-Universität, Marburg, 1994-1995
Speaker of the DFG-Schwerpunktprogramm "Radicals in Enzymatic Catalysis" 1998-2006
Speaker of the Graduiertenkolleg "Proteinfunction at the Atomic Level" since 1999-2006
Editor of "Archives of Microbiology" and "FEMS Microbiology Letters"
Research area: Electron bifurcation and amino acid fermentations at the origin of life
There is increasing support for the hypothesis that the first organisms on Earth were autotrophs, similar to the extant acetogenic bacteria and methanogenic archaea. If the first cells were indeed autotrophs, how did the first heterotrophs arise, and what was their substrate? In a recent article (Schönheit et al. 2016), we proposed that autotrophs were the substrate for the first chemoorganoheterotrophs. Since prokaryotes like Escherichia coli consist of 55% protein and 25% nucleic acids, amino acid, nucleobase and ribose fermentations might have been the first forms of heterotrophic energy and carbon metabolism.
The first amino acid fermentations could have been similar to those occurring in extant archaea and bacteria. Clostridial amino acid fermentations have been studied by the author since 1970, when he was a postdoc in Horace Albert Barker’s laboratory at the University of California at Berkeley. Amino acid fermentations are redox reactions. One amino acid is oxidized and another or the same acts as electron acceptor. In the oxidative branch of these fermentations, energy is conserved by substrate level phosphorylation, whereas the reductive branch usually applies H+ or Na+-gradient phosphorylation for ATP synthesis. The oxidative branches follow the reverse of the biosynthetic pathways, which have been established already by the autotrophs and are conserved in all extant organisms. The reductive branches, however, must have been developed by the first heterotrophs and are thought to be similar to those of the amino acid fermenting clostridia. The study of these anaerobic bacteria revealed a plethora of exciting unusual radical reactions, which are absent in other organisms. A special feature of the clostridia is the formation of butyrate via reduction of crotonyl-CoA to butyryl-CoA by NADH. This exergonic reaction is coupled to the endergonic reduction of the electron carriers ferredoxin or flavodoxin also by NADH, a process called electron bifurcation. The reduced electron carriers are re-oxidized by protons yielding hydrogen or by NAD+ catalyzed by a membrane enzyme (Rnf), whereby an electrochemical Na+ gradient is generated. Electron bifurcation is wide spread among anaerobes, especially in acetogenic bacteria and methanogenic archaea, in which this process enhances the reductive power of hydrogen for CO2 reduction. Hence electron bifurcation has been essential for the origin of life.