Structure and function of a bacterial ion (Na+)-translocating ferredoxin: NAD+-oxidoreductase (Rnf)

• Applicant: Professor Dr. Volker Müller
• Subject Area: Metabolism, Biochemistry and Genetics of Microorganisms
• Term: from 2011 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 206018227

• Final Report Year: 2021

Final Report Abstract

This project, the identification of the primary sodium ion pump in the acetogen A. woodii, started 20 years ago in 2001. In the beginning, we and others speculated that the primary pump is part of the WLP, possibly the methyltransferase, as in methanogenic archaea. However, research over the years disproved this hypothesis. After 10 years of chasing a ghost a new idea was born in a big melting point of ideas, data, genome sequences under contribution of Profs. Buckel, Gottschalk and Thauer. The exciting idea was that many anaerobes may have a respiratory ferredoxin:NAD oxidoreductase that, in acetogens, may channel electrons to the WLP enzymes. In the last ten years, we have provided a wealth of direct and indirect data published in many papers that the primary, Na+ translocating respiratory enzyme in A. woodii is the Rnf complex that catalyzes ferredoxin-dependent NAD reduction with concomittant Na+ export.

Publications

• (2018) The Rnf complex is an energy coupled transhydrogenase essential to reversibly link cellular NADH and ferredoxin pools in the acetogen Acetobacterium woodii. J. Bacteriol. 00357-18
  Westphal, L., Wiechmann, A., Baker, J., Minton, N.P., Müller, V.
  (See online at https://doi.org/10.1128/jb.00357-18)
• (2020) The Rnf complex from the acetogenic bacterium Acetobacterium woodii: Purification and characterization of RnfC and RnfB. Biochim. Biophys. Acta - Bioenerg. 1861 : 148263
  Kuhns, M., Schuchmann, V., Schmidt, S., Friedrich, T., Wiechmann, A., Müller, V.
  (See online at https://doi.org/10.1016/j.bbabio.2020.148263)
• (2020) The Rnf complex is a Na+ coupled respiratory enzyme in a fermenting bacterium, Thermotoga maritima. Commun. Biol. 3 : 431
  Kuhns, M., Trifunović, D., Huber, H., Müller, V.
  (See online at https://doi.org/10.1038/s42003-020-01158-y)
• (2021) Homologous production, one step purification and proof of Na+ transport by the Rnf complex from Acetobacterium woodii, a model for acetogenic conversion of C1 substrates to biofuels. Biotechnol. Biofuels 13 : 208
  Wiechmann, A., Trifunović, D., Klein, S., Müller, V.
  (See online at https://doi.org/10.1186/s13068-020-01851-4)