CoChat
Sign Up
Cited by 797Metalloenzymes and iron-sulfur proteinsAnaerobic Digestion and Biogas ProductionEnzyme Structure and Function

Energy conservation via electron bifurcating ferredoxin reduction and proton/Na+ translocating ferredoxin oxidation

Open access
Buckel, Wolfgang, Thauer, Rudolf K.·2013·Biochimica et Biophysica Acta (BBA) - Bioenergetics
DOI 10.1016/j.bbabio.2012.07.002
Open this paper in CoChat — free accountOpen PDF

Abstract

The review describes four flavin-containing cytoplasmatic multienzyme complexes from anaerobic bacteria and archaea that catalyze the reduction of the low potential ferredoxin by electron donors with higher potentials, such as NAD(P)H or H(2) at ≤ 100 kPa. These endergonic reactions are driven by concomitant oxidation of the same donor with higher potential acceptors such as crotonyl-CoA, NAD(+) or heterodisulfide (CoM-S-S-CoB). The process called flavin-based electron bifurcation (FBEB) can be regarded as a third mode of energy conservation in addition to substrate level phosphorylation (SLP) and electron transport phosphorylation (ETP). FBEB has been detected in the clostridial butyryl-CoA dehydrogenase/electron transferring flavoprotein complex (BcdA-EtfBC), the multisubunit [FeFe]hydrogenase from Thermotoga maritima (HydABC) and from acetogenic bacteria, the [NiFe]hydrogenase/heterodisulfide reductase (MvhADG-HdrABC) from methanogenic archaea, and the transhydrogenase (NfnAB) from many Gram positive and Gram negative bacteria and from anaerobic archaea. The Bcd/EtfBC complex that catalyzes electron bifurcation from NADH to the low potential ferredoxin and to the high potential crotonyl-CoA has already been studied in some detail. The bifurcating protein most likely is EtfBC, which in each subunit (βγ) contains one FAD. In analogy to the bifurcating complex III of the mitochondrial respiratory chain and with the help of the structure of the human ETF, we propose a conformational change by which γ-FADH(-) in EtfBC approaches β-FAD to enable the bifurcating one-electron transfer. The ferredoxin reduced in one of the four electron bifurcating reactions can regenerate H(2) or NADPH, reduce CO(2) in acetogenic bacteria and methanogenic archaea, or is converted to ΔμH(+)/Na(+) by the membrane-associated enzyme complexes Rnf and Ech, whereby NADH and H(2) are recycled, respectively. The mainly bacterial Rnf complexes couple ferredoxin oxidation by NAD(+) with proton/sodium ion translocation and the more diverse energy converting [NiFe]hydrogenases (Ech) do the same, whereby NAD(+) is replaced by H(+). Many organisms also use Rnf and Ech in the reverse direction to reduce ferredoxin driven by ΔμH(+)/Na(+). Finally examples are shown, in which the four bifurcating multienzyme complexes alone or together with Rnf and Ech are integrated into energy metabolisms of nine anaerobes. This article is part of a Special Issue entitled: The evolutionary aspects of bioenergetic systems.

The claims and statistics of this paper haven’t been checked yet.

Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.

A few free checks a day · papers already verified open instantly · results are public

Integrity signals

Registry

Crossref · 10.1016/j.bbabio.2012.07.002

Cites

123 of 123 references verified0 citation errors · 0 not checkable

Statistics

Claims the paper makes

The claims and statistics of this paper haven’t been checked yet.

Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.

A few free checks a day · papers already verified open instantly · results are public

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • Acetogens and methanogens depend upon CoFeS and the acetyl-CoA pathway for growth, are extremely O2-sensitive, and use the anaerobic corrin synthesis pathway.

    “Third, acetogens and methanogens themselves, which depend upon CoFeS and the acetyl‐CoA pathway for growth [48, 49, 78], are extremely O2‐sensitive and use the anaerobic corrin synthesis pathway.”

    From Evidence for corrin biosynthesis in the last universal common ancestor (2025) · cites this paper as [78]

    Sections 4.5 and 4.6 describe ferredoxin-dependent reactions in methanogens and acetogens, including CO dehydrogenase in acetogens and acetyl-CoA-related anabolic reactions in methanogens. They do not establish the cited clause’s broader claim that both groups depend on CoFeS and the acetyl-CoA pathway for growth. The citation is attached to that dependency clause, not to the subsequent O2-sensitivity and corrin-synthesis assertions. (LLM, conf=0.78)

    Experimental — accuracy not yet measured

  • The acetyl-CoA pathway is integral to ATP synthesis from H2 and CO2 in acetogens and methanogens.

    “the acetyl‐CoA pathway is integral to ATP synthesis from H2 and CO2 in acetogens and methanogens [78, 128].”

    From Evidence for corrin biosynthesis in the last universal common ancestor (2025) · cites this paper as [78]

    Section 4.6 links acetogenesis from H₂ and CO₂ to ATP generation, while noting that how the ATP is generated remains unresolved. Section 4.5 instead describes ATP-generating energy metabolism in methanogens through methane formation; its mention of acetyl-CoA concerns anabolic pyruvate formation, not the pathway responsible for ATP synthesis. Page numbers are unavailable in our copy. (LLM, conf=0.88)

    Experimental — accuracy not yet measured

  • This required the origin of additional complexes essential for methanogens and acetogens, namely, hydrogenases and flavin-based electron bifurcation, the precursor of which was Fe0-dependent ferredoxin reduction with H2 under hydrothermal conditions.

    “This required the origin of additional complexes essential for methanogens and acetogens, namely, hydrogenases and flavin‐based electron bifurcation [78], the precursor of which was Fe0‐dependent ferredoxin reduction with H2 under hydrothermal conditions [79].”

    From Evidence for corrin biosynthesis in the last universal common ancestor (2025) · cites this paper as [78]

    Split into 2 atoms — 0 confirmed, 1 partially supported, 0 disputed, 0 misattributed, 1 unverifiable. Expand the claim to see per-atom verdicts.

    Experimental — accuracy not yet measured

  • The main energy currency in methanogens that lack cytochromes is low-potential-reduced ferredoxin, Fdred.

    “The main energy currency is low-potential-reduced ferredoxin, Fdred [143].”

    From Early bioenergetic evolution (2013) · cites this paper as [143]

    Section 4.5 (page unavailable) says cytochrome-free methanogens generate reduced ferredoxin by electron bifurcation and require it for the first step of methanogenesis from CO₂. Section 2 describes its low redox potential. The paper also identifies a sodium-ion potential as an energy-conservation mechanism, so it does not establish reduced ferredoxin as the *main* energy currency. (LLM, conf=0.82)

    Experimental — accuracy not yet measured

  • Per mol of acetate, about 0.25 mol of ATP is generated.

    “Per mol of acetate, about 0.25 mol of ATP is generated [143].”

    From Early bioenergetic evolution (2013) · cites this paper as [143]

    Section 4.6 predicts a yield of 0.25 mol ATP per mol of acetic acid formed from H₂ and CO₂ in a metabolic scheme for A. woodii. The citing sentence states the yield as a general fact per mol of acetate, without that organism, pathway, or predictive qualification. (LLM, conf=0.83)

    Experimental — accuracy not yet measured

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

The self-check needs the paper’s full text.

Cites

Flagged first, then by citations

1 of the 124 references couldn’t be matched to a known paper.

Research works printed but not linked: 2

  1. [59]59. B. Buchenau, Are there tetrahydrofolate specific enzymes in archaea and tetrahydromethanopterin specific enzymes in acetogenic bacteria? Diploma Thesis, Fachbereich Biologie, Philipps-University, Marburg, 2001.
  2. [83]83. E. Biegel, V. Müller, Bacterial Na + -translocating ferredoxin:NAD + oxidoreduc- tase, Proc. Natl. Acad. Sci. U. S. A. 107 (2010) 18138-18142.

Cited by

Sorted by citations

Related

Authors
Buckel, W., & Thauer, R. K.
Affiliations
Philipps University of Marburg (DE)
Corresponding author
Buckel, Wolfgang
ORCID
Venue
Biochimica et Biophysica Acta (BBA) - Bioenergetics
Publisher
Elsevier BV
Published
2013-02
Volume
1827
Issue
2
Pages
94-113
ISSN
0005-2728 (ISSN-L)
DOI
10.1016/j.bbabio.2012.07.002
OpenAlex
W2172371128
Cited by
797
References
124
Citations by year
2026: 46 · 2025: 50 · 2024: 51 · 2023: 35 · 2022: 65 · 2021: 41 · 2020: 72 · 2019: 67 · 2018: 82 · 2017: 67 · 2016: 88 · 2015: 39 · 2014: 46 · 2013: 38 · 2012: 8
FWCI
1.80
Type
journal article
Language
en
Open access
Licence
Locations
  • Biochimica et Biophysica Acta (BBA) - Bioenergetics (publishedVersion)
  • PubMed (publishedVersion)
  • Max Planck Institute for Plasma Physics (submittedVersion)
  • MPG.PuRe (Max Planck Society) (submittedVersion)
Funders
  • Max-Planck-Gesellschaft
  • Fonds der Chemischen Industrie
Topics
  • Physical Sciences › Energy › Renewable Energy, Sustainability and the Environment › Metalloenzymes and iron-sulfur proteins
  • Physical Sciences › Engineering › Building and Construction › Anaerobic Digestion and Biogas Production
  • Physical Sciences › Materials Science › Materials Chemistry › Enzyme Structure and Function
Keywords
energy conservation, anaerobic bacteria, methanogenic archaea, acetogenic bacteria, [FeFe]-hydrogenase, transhydrogenase, Rnf complex, electron transport phosphorylation
MeSH terms
Cytoplasm, Electrons, Energy Metabolism, Ferredoxins, Flavins, Humans, Oxidation-Reduction, Protons, Sodium, Ion Transport

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review