The enzyme is a complex of a flavin-containing dehydrogenase component (Bcd) and an electron-transfer flavoprotein dimer (EtfAB). The enzyme complex, isolated from the bacteria Acidaminococcus fermentans and butanoate-producing Clostridia species, couples the exergonic reduction of (E)-but-2-enoyl-CoA to butanoyl-CoA by NADH to the endergonic reduction of ferredoxin by NADH, using electron bifurcation to overcome the steep energy barrier in ferredoxin reduction.
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SYSTEMATIC NAME
IUBMB Comments
butanoyl-CoA:NAD+, ferredoxin oxidoreductase
The enzyme is a complex of a flavin-containing dehydrogenase component (Bcd) and an electron-transfer flavoprotein dimer (EtfAB). The enzyme complex, isolated from the bacteria Acidaminococcus fermentans and butanoate-producing Clostridia species, couples the exergonic reduction of (E)-but-2-enoyl-CoA to butanoyl-CoA by NADH to the endergonic reduction of ferredoxin by NADH, using electron bifurcation to overcome the steep energy barrier in ferredoxin reduction.
i.e. crotonyl-CoA. NADH reduces beta-FAD of electron transferring flavoprotein, which bifurcates one electron to butanoyl-CoA dehydrogenase via FAD and the other to ferredoxin. Electron transferring flavoprotein (EtfAf) contains one FAD (alpha-FAD) in subunit alpha and a second FAD (beta-FAD) in subunit beta. The distance between the two isoalloxazine rings is 18 A°. The EtfAf-NAD+ complex structure reveals beta-FAD as acceptor of the hydride of NADH. The formed beta-FADH- is considered as the bifurcating electron donor. As a result of a domain movement, alpha-FAD is able to approach beta-FADH- by about 4 A and to take up one electron yielding a stable anionic semiquinone, alpha-FAD-/*, which donates this electron further to the FAD of butanoyl-CoA dehydrogenase BcdAf after a second domain movement. The remaining nonstabilized neutral semiquinone, beta-FADH*, immediately reduces ferredoxin. This electron flow from beta-FADH* to ferredoxin is only accomplished if the thermodynamically more favorable electron transfer to alpha-FAD-*. is prevented. Therefore, after the first electron transfer to alpha-FAD, a rotation is postulated of domain II toward the FAD binding site of butanoyl-CoA dehydrogenase BcdAf (based on spectroscopic and structural data). This conformational change, concomitantly, also reduces the distance between alpha-FAD-* and FAD from butanoyl-CoA dehydrogenase from about 30 to about 10 A. Thus, alpha-FAD embedded into the weakly associated domain II serves as a shuttle between the electron-donating beta-FADH- and the electron-accepting FAD of butanoyl-CoA dehydrogenase. Repetition leads to reduction of crotonyl-CoA
i.e. crotonyl-CoA. NADH reduces beta-FAD of electron transferring flavoprotein, which bifurcates one electron to butanoyl-CoA dehydrogenase via FAD and the other to ferredoxin. Electron transferring flavoprotein (EtfAf) contains one FAD (alpha-FAD) in subunit alpha and a second FAD (beta-FAD) in subunit beta. The distance between the two isoalloxazine rings is 18 A°. The EtfAf-NAD+ complex structure reveals beta-FAD as acceptor of the hydride of NADH. The formed beta-FADH- is considered as the bifurcating electron donor. As a result of a domain movement, alpha-FAD is able to approach beta-FADH- by about 4 A and to take up one electron yielding a stable anionic semiquinone, alpha-FAD-/*, which donates this electron further to the FAD of butanoyl-CoA dehydrogenase BcdAf after a second domain movement. The remaining nonstabilized neutral semiquinone, beta-FADH*, immediately reduces ferredoxin. This electron flow from beta-FADH* to ferredoxin is only accomplished if the thermodynamically more favorable electron transfer to alpha-FAD-*. is prevented. Therefore, after the first electron transfer to alpha-FAD, a rotation is postulated of domain II toward the FAD binding site of butanoyl-CoA dehydrogenase BcdAf (based on spectroscopic and structural data). This conformational change, concomitantly, also reduces the distance between alpha-FAD-* and FAD from butanoyl-CoA dehydrogenase from about 30 to about 10 A. Thus, alpha-FAD embedded into the weakly associated domain II serves as a shuttle between the electron-donating beta-FADH- and the electron-accepting FAD of butanoyl-CoA dehydrogenase. Repetition leads to reduction of crotonyl-CoA
the energy-rich reduced ferredoxin contributes to the energy conservation of the organism either by regeneration of NADH via the H+/Na+-pumping ferredoxin-NAD+ reductase also (Rnf) or by reduction of protons to H2, which increases the substrate-level phosphorylation via the oxidative branch of the fermentation
the energy-rich reduced ferredoxin contributes to the energy conservation of the organism either by regeneration of NADH via the H+/Na+-pumping ferredoxin-NAD+ reductase also (Rnf) or by reduction of protons to H2, which increases the substrate-level phosphorylation via the oxidative branch of the fermentation
the energy-rich reduced ferredoxin contributes to the energy conservation of the organism either by regeneration of NADH via the H+/Na+-pumping ferredoxin-NAD+ reductase also (Rnf) or by reduction of protons to H2, which increases the substrate-level phosphorylation via the oxidative branch of the fermentation
the energy-rich reduced ferredoxin contributes to the energy conservation of the organism either by regeneration of NADH via the H+/Na+-pumping ferredoxin-NAD+ reductase also (Rnf) or by reduction of protons to H2, which increases the substrate-level phosphorylation via the oxidative branch of the fermentation
the electron transferring flavoprotein (EtfAf) contains one FAD (alpha-FAD) in subunit alpha and a second FAD (beta-FAD) in subunit beta. butanoyl-CoA dehydrogenase also contains FAD. beta-FAD of the the electron transferring flavoprotein is the acceptor of the hydride of NADH. The formed beta-FADH- is considered as the bifurcating electron donor. As a result of a domain movement, alpha-FAD is able to approach beta-FADH- by about 4 A and to takeup one electron yielding a stable anionic semiquinone, alpha-FAD-/* , which donates this electron further to the FAD of butanoyl-CoA dehydrogenase BcdAf after a second domain movement. The remaining nonstabilized neutral semiquinone, beta-FADH*, immediately reduces ferredoxin. This electron flow from beta-FADH* to ferredoxin is only accomplished if the thermodynamically more favorable electron transfer to alpha-FAD-*. is prevented. Therefore, after the first electron transfer to alpha-FAD, a rotation is postulated of domain II toward the FAD binding site of butanoyl-CoA dehydrogenase BcdAf (based on spectroscopic and structural data). This conformational change, concomitantly, also reduces the distance between alpha-FAD-* and FAD from butanoyl-CoA dehydrogenase from about 30 to about 10 A. Thus, alpha-FAD embedded into the weakly associated domain II serves as a shuttle between the electron-donating beta-FADH- and the electron-accepting FAD of butanoyl-CoA dehydrogenase. Repetition leads to reduction of crotonyl-CoA
D2RIQ2: electron transfer flavoprotein beta-subunit, D2RIQ3: electron transfer flavoprotein alpha-subunit, D2RL84: acyl-CoA dehydrogenase domain protein
D2RIQ2: electron transfer flavoprotein beta-subunit, D2RIQ3: electron transfer flavoprotein alpha-subunit, D2RL84: acyl-CoA dehydrogenase domain protein
the energy-rich reduced ferredoxin contributes to the energy conservation of the organism either by regeneration of NADH via the H+/Na+-pumping ferredoxin-NAD+ reductase also (Rnf) or by reduction of protons to H2, which increases the substrate-level phosphorylation via the oxidative branch of the fermentation
the energy-rich reduced ferredoxin contributes to the energy conservation of the organism either by regeneration of NADH via the H+/Na+-pumping ferredoxin-NAD+ reductase also (Rnf) or by reduction of protons to H2, which increases the substrate-level phosphorylation via the oxidative branch of the fermentation
because electron transferring flavoprotein (EtfAf) and butanoyl-CoA dehydrogenase (BcdAf) are separated proteins in solution, a transient Bcd-Etf complex is sufficient to perform a bifurcation process. Electron transferring flavoprotein (EtfAf) is a heterodimer with a molecular mass of around 66 kDa (theoretically 37600 + 28400 Da). Butanoyl-CoA dehydrogenase (BcdAf) is homotetrameric flavoprotein (4 * 42000 Da)
because electron transferring flavoprotein (EtfAf) and butanoyl-CoA dehydrogenase (BcdAf) are separated proteins in solution, a transient Bcd-Etf complex is sufficient to perform a bifurcation process. Electron transferring flavoprotein (EtfAf) is a heterodimer with a molecular mass of around 66 kDa (theoretically 37600 + 28400 Da). Butanoyl-CoA dehydrogenase (BcdAf) is homotetrameric flavoprotein (4 * 42000 Da)
because electron transferring flavoprotein (EtfAf) and butanoyl-CoA dehydrogenase (BcdAf) are separated proteins in solution, a transient Bcd-Etf complex is sufficient to perform a bifurcation process. Electron transferring flavoprotein (EtfAf) is a heterodimer with a molecular mass of around 66 kDa (theoretically 37600 + 28400 Da). Butanoyl-CoA dehydrogenase (BcdAf) is homotetrameric flavoprotein (4 * 42000 Da)
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OXIDATION STABILITY
ORGANISM
UNIPROT
LITERATURE
although EtfAf and BcdAf are stable under air, all the experiments are performed in an anaerobic chamber under an atmosphere of 95% N2 and 5% H2, since ferredoxin and the reduced forms of flavin are oxygen-sensitive
engineering of Clostridum sp. MT1962 by elimination of phosphotransacetylase and acetaldehyde dehydrogenase along with integration to chromosome synthetic thiolase, 3-hydroxybutyryl-CoA dehydrogenase, crotonase, butyryl-CoA dehydrogenase, butyraldehyde dehydrogenase, and NAD-dependent butanol dehydrogenase. Th resulting strain loses production of ethanol and acetate while initiated the production of 297 mM of n-butanol
engineering of Clostridum sp. MT1962 by elimination of phosphotransacetylase and acetaldehyde dehydrogenase along with integration to chromosome synthetic thiolase, 3-hydroxybutyryl-CoA dehydrogenase, crotonase, butyryl-CoA dehydrogenase, butyraldehyde dehydrogenase, and NAD-dependent butanol dehydrogenase. Th resulting strain loses production of ethanol and acetate while initiated the production of 297 mM of n-butanol
Effect of an Oxygen-Tolerant Bifurcating Butyryl Coenzyme A Dehydrogenase/Electron-Transferring Flavoprotein Complex from Clostridium difficile on Butyrate Production in Escherichia coli
J. Bacteriol.
195
3704-3713
2013
Clostridioides difficile (Q18AQ1 and Q18AQ6 and Q18AQ5), Clostridioides difficile, Clostridioides difficile DSM 1296T (Q18AQ1 and Q18AQ6 and Q18AQ5)
Studies on the mechanism of electron bifurcation catalyzed by electron transferring flavoprotein (Etf) and butyryl-CoA dehydrogenase (Bcd) of Acidaminococcus fermentans
J. Biol. Chem.
289
5145-5157
2013
Acidaminococcus fermentans (D2RIQ2 and D2RIQ3 and D2RL84), Acidaminococcus fermentans DSM 20731 (D2RIQ2 and D2RIQ3 and D2RL84)
Involvement of NADH:acceptor oxidoreductase and butyryl coenzyme A dehydrogenase in reversed electron transport during syntrophic butyrate oxidation by Syntrophomonas wolfei
Selective n-Butanol production by Clostridium sp. MTButOH1365 during continuous synthesis gas fermentation due to expression of synthetic thiolase, 3-hydroxy butyryl-CoA dehydrogenase, crotonase, butyryl-CoA dehydrogenase, butyraldehyde dehydrogenase, and NAD-dependent butanol dehydrogenase