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Updated: Jun 8, 2026
06:01
EPR Monitored Redox Titration of the Cofactors of Saccharomyces cerevisiae Nar1
Published on: November 26, 2014
Bacterial Na+-translocating ferredoxin:NAD+ oxidoreductase
1Department of Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University Frankfurt/Main, 60438 Frankfurt, Germany.
Summary
Acetobacterium woodii uses caffeate respiration, a unique anaerobic process. Its ferredoxin:NAD(+) oxidoreductase (Fno) activity directly couples electron transfer to sodium ion transport, acting as a primary sodium pump.
Area of Science:
- Microbiology
- Bioenergetics
- Biochemistry
Background:
- Acetobacterium woodii performs unique Na(+)-motive anaerobic respiration using caffeate.
- The central membrane-bound reaction identified is ferredoxin:NAD(+) oxidoreductase (Fno) activity.
Purpose of the Study:
- To investigate the mechanism of Na(+) transport coupled to Fno activity in A. woodii.
- To determine if Fno activity is directly linked to Na(+) translocation and identify the responsible complex.
Main Methods:
- Utilized inverted membrane vesicles of A. woodii.
- Measured Na(+) transport coupled to Fno activity using electron transfer from reduced ferredoxin to NAD(+).
- Employed inhibitor studies with sodium ionophores and protonophores.
Main Results:
- Demonstrated direct coupling of Fno activity to electrogenic Na(+) transport into vesicles.
- Showed Na(+) accumulation was inhibited by sodium ionophores but not protonophores.
- Provided evidence suggesting the Rnf complex catalyzes Fno activity coupled to Na(+) translocation.
Conclusions:
- Fno activity in A. woodii functions as a primary Na(+) pump, directly coupling electron transfer to Na(+) transport.
- This mechanism represents an early evolutionary strategy for energy conservation, expanding known redox ranges for life.
- Offers a mechanistic explanation for anaerobic bacterial lifestyles and the energetic driving force for ferredoxin reduction in some aerobic bacteria.
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