title: Discovery of a ferredoxin:NAD+-oxidoreductase (Rnf) in Acetobacterium woodii: a novel potential coupling site in acetogens.
abstract: Acetogens use the Wood-Ljungdahl pathway for reduction of carbon dioxide to acetate. This pathway not only allows reoxidation of reducing equivalents during heterotrophic growth but also supports chemolithoautotrophic growth on H(2) + CO(2). The latter argues for this pathway being a source for net energy conservation, but the mechanism involved remains unknown. In addition to CO(2), acetogens can use alternative electron acceptors, such as nitrate or caffeate. Caffeate respiration in the model acetogen Acetobacterium woodii is coupled to energy conservation via a chemiosmotic mechanism, with Na(+) as coupling ion. The pathway and its bioenergetics were solved in some detail very recently. This review focuses on the regulation of caffeate respiration, describes the enyzmes involved, summarizes the evidence for a potential Na(+)-translocating ferredoxin:NAD(+)-oxidoreductase (Rnf complex) as a new coupling site, and hypothesizes on the role of this Rnf complex in the Wood-Ljungdahl pathway.
authors: Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University, Frankfurt am Main, Germany. vmueller@bio.uni-frankfurt.de
authors: Volker
authors: V
authors: Müller
authors: Frank
authors: F
authors: Imkamp
authors: Eva
authors: E
authors: Biegel
authors: Silke
authors: S
authors: Schmidt
authors: Sabrina
authors: S
authors: Dilling
mesh_terms: D045855:Acetobacterium / Q000201:enzymology* / Q000254:growth & development; D000105:Acetyl Coenzyme A / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism; D004579:Electron Transport; D005288:Ferredoxins / Q000378:metabolism; D006859:Hydrogen / Q000378:metabolism; D007700:Kinetics; D009243:NAD / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism*; D010101:Oxygen Consumption
chemical_list: D005288:Ferredoxins; D009243:NAD; D002245:Carbon Dioxide; D000105:Acetyl Coenzyme A; D006859:Hydrogen; D010088:Oxidoreductases; C028878:ferredoxin-NAD+ reductase