TY  - JOUR
A1  - Schuchmann, Kai
A1  - Müller, Volker
T1  - A bacterial electron-bifurcating hydrogenase
T2  - Journal of biological chemistry
N2  - The Wood-Ljungdahl pathway of anaerobic CO(2) fixation with hydrogen as reductant is considered a candidate for the first life-sustaining pathway on earth because it combines carbon dioxide fixation with the synthesis of ATP via a chemiosmotic mechanism. The acetogenic bacterium Acetobacterium woodii uses an ancient version of the pathway that has only one site to generate the electrochemical ion potential used to drive ATP synthesis, the ferredoxin-fueled, sodium-motive Rnf complex. However, hydrogen-based ferredoxin reduction is endergonic, and how the steep energy barrier is overcome has been an enigma for a long time. We have purified a multimeric [FeFe]-hydrogenase from A. woodii containing four subunits (HydABCD) which is predicted to have one [H]-cluster, three [2Fe2S]-, and six [4Fe4S]-clusters consistent with the experimental determination of 32 mol of Fe and 30 mol of acid-labile sulfur. The enzyme indeed catalyzed hydrogen-based ferredoxin reduction, but required NAD(+) for this reaction. NAD(+) was also reduced but only in the presence of ferredoxin. NAD(+) and ferredoxin reduction both required flavin. Spectroscopic analyses revealed that NAD(+) and ferredoxin reduction are strictly coupled and that they are reduced in a 1:1 stoichiometry. Apparently, the multimeric hydrogenase of A. woodii is a soluble energy-converting hydrogenase that uses electron bifurcation to drive the endergonic ferredoxin reduction by coupling it to the exergonic NAD(+) reduction.
KW  - Bioenergetics
KW  - Electron Transport
KW  - Enzyme Mechanisms
KW  - Hydrogenase
KW  - Iron-Sulfur Protein
KW  - Metabolism
KW  - Metalloenzymes
KW  - Microbiology
KW  - Acetogenesis
KW  - Electron Bifurcation
Y1  - 2021
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/76653
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-766532
SN  - 0021-9258
VL  - 287
IS  - 37
SP  - 31165
EP  - 31171
PB  - American Society for Biochemistry and Molecular Biology Publications
CY  - Bethesda, Md
ER  -