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Information on EC 1.8.7.3 - ferredoxin:CoB-CoM heterodisulfide reductase
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1.8.7.3 ferredoxin:CoB-CoM heterodisulfide reductaseIUBMB Comments
HdrABC is an enzyme complex that is found in most methanogens and catalyses the reduction of the CoB-CoM heterodisulfide back to CoB and CoM. HdrA contains a FAD cofactor that acts as the entry point for electrons, which are transferred via HdrC to the HdrB catalytic subunit. One form of the enzyme from Methanosarcina acetivorans (HdrA2B2C2) can also catalyse EC 1.8.98.4, coenzyme F420:CoB-CoM heterodisulfide,ferredoxin reductase. cf. EC 1.8.98.5, H2:CoB-CoM heterodisulfide,ferredoxin reductase, EC 1.8.98.6, formate:CoB-CoM heterodisulfide,ferredoxin reductase, and EC 1.8.98.1, dihydromethanophenazine:CoB-CoM heterodisulfide reductase.
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The expected taxonomic range for this enzyme is: Bacteria, Archaea
Reaction Schemes
2
+
+
=
2
+
+
2
2
oxidized ferredoxin [iron-sulfur] cluster
+
+
=
2
reduced ferredoxin [iron-sulfur] cluster
+
+
2
Synonyms
cob-com heterodisulfide reductase, hdra1b1c1, 
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SYNONYM 
ORGANISM
UNIPROT
COMMENTARY 
LITERATURE
CoB-CoM heterodisulfide reductase
HDR
hdrA1B1C1
-
-
-
-
hdrA2B2C2
-
-
-
-
HdrABC
HdrB
heterodisulfide reductase
additional information
CoB-CoM heterodisulfide reductase
-
CoB-CoM heterodisulfide reductase
-
-
HdrABC
-
-
-
-
heterodisulfide reductase
P60200; Q58153; Q58273; Q58154; Q58274
-
heterodisulfide reductase
P60200; Q58153; Q58273; Q58154; Q58274
-
-
heterodisulfide reductase
P60200; Q58153; Q58273; Q58154; Q58274
-
-
heterodisulfide reductase
P60200; Q58153; Q58273; Q58154; Q58274
-
-
heterodisulfide reductase
P60200; Q58153; Q58273; Q58154; Q58274
-
-
heterodisulfide reductase
P60200; Q58153; Q58273; Q58154; Q58274
-
-
heterodisulfide reductase
-
heterodisulfide reductase
-
-
additional information
P60200; Q58153; Q58273; Q58154; Q58274
cf. EC 1.8.98.1, EC 1.8.98.4, and EC 1.8.98.5
additional information
P60200; Q58153; Q58273; Q58154; Q58274
cf. EC 1.8.98.1, EC 1.8.98.4, and EC 1.8.98.5
-
additional information
P60200; Q58153; Q58273; Q58154; Q58274
cf. EC 1.8.98.1, EC 1.8.98.4, and EC 1.8.98.5
-
additional information
P60200; Q58153; Q58273; Q58154; Q58274
cf. EC 1.8.98.1, EC 1.8.98.4, and EC 1.8.98.5
-
additional information
P60200; Q58153; Q58273; Q58154; Q58274
cf. EC 1.8.98.1, EC 1.8.98.4, and EC 1.8.98.5
-
additional information
P60200; Q58153; Q58273; Q58154; Q58274
cf. EC 1.8.98.1, EC 1.8.98.4, and EC 1.8.98.5
-
additional information
-
cf. EC 1.8.98.1, EC 1.8.98.4, and EC 1.8.98.5
additional information
cf. EC 1.8.98.1, EC 1.8.98.4, and EC 1.8.98.5
additional information
cf. EC 1.8.98.1, EC 1.8.98.4, and EC 1.8.98.5
-
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REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT
LITERATURE
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM = 2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM = 2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
-
-
-
-
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM = 2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
reaction mechanism, overview
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM = 2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
subunit HdrB of heterodisulfide reductase (HdrABC-MvhAGD) contains two noncubane [4Fe-4S] clusters tht are involved in reduction activity. The heterodisulfide is clamped between the two noncubane [4Fe-4S] clusters and homolytically cleaved, forming coenzyme M and B bound to each iron. Coenzymes are consecutively released upon one-by-one electron transfer
-
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM = 2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
subunit HdrB of heterodisulfide reductase (HdrABC-MvhAGD) contains two noncubane [4Fe-4S] clusters tht are involved in reduction activity. The heterodisulfide is clamped between the two noncubane [4Fe-4S] clusters and homolytically cleaved, forming coenzyme M and B bound to each iron. Coenzymes are consecutively released upon one-by-one electron transfer
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM = 2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
subunit HdrB of heterodisulfide reductase (HdrABC-MvhAGD) contains two noncubane [4Fe-4S] clusters tht are involved in reduction activity. The heterodisulfide is clamped between the two noncubane [4Fe-4S] clusters and homolytically cleaved, forming coenzyme M and B bound to each iron. Coenzymes are consecutively released upon one-by-one electron transfer
P60200; Q58153; Q58273; Q58154; Q58274
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM = 2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
subunit HdrB of heterodisulfide reductase (HdrABC-MvhAGD) contains two noncubane [4Fe-4S] clusters tht are involved in reduction activity. The heterodisulfide is clamped between the two noncubane [4Fe-4S] clusters and homolytically cleaved, forming coenzyme M and B bound to each iron. Coenzymes are consecutively released upon one-by-one electron transfer
-
-
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM = 2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
subunit HdrB of heterodisulfide reductase (HdrABC-MvhAGD) contains two noncubane [4Fe-4S] clusters tht are involved in reduction activity. The heterodisulfide is clamped between the two noncubane [4Fe-4S] clusters and homolytically cleaved, forming coenzyme M and B bound to each iron. Coenzymes are consecutively released upon one-by-one electron transfer
-
-
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM = 2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
subunit HdrB of heterodisulfide reductase (HdrABC-MvhAGD) contains two noncubane [4Fe-4S] clusters tht are involved in reduction activity. The heterodisulfide is clamped between the two noncubane [4Fe-4S] clusters and homolytically cleaved, forming coenzyme M and B bound to each iron. Coenzymes are consecutively released upon one-by-one electron transfer
-
-
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM = 2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
subunit HdrB of heterodisulfide reductase (HdrABC-MvhAGD) contains two noncubane [4Fe-4S] clusters tht are involved in reduction activity. The heterodisulfide is clamped between the two noncubane [4Fe-4S] clusters and homolytically cleaved, forming coenzyme M and B bound to each iron. Coenzymes are consecutively released upon one-by-one electron transfer
-
-
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM = 2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
reaction mechanism, overview
-
-
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM = 2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
subunit HdrB of heterodisulfide reductase (HdrABC-MvhAGD) contains two noncubane [4Fe-4S] clusters tht are involved in reduction activity. The heterodisulfide is clamped between the two noncubane [4Fe-4S] clusters and homolytically cleaved, forming coenzyme M and B bound to each iron. Coenzymes are consecutively released upon one-by-one electron transfer
-
-
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM = 2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
subunit HdrB of heterodisulfide reductase (HdrABC-MvhAGD) contains two noncubane [4Fe-4S] clusters tht are involved in reduction activity. The heterodisulfide is clamped between the two noncubane [4Fe-4S] clusters and homolytically cleaved, forming coenzyme M and B bound to each iron. Coenzymes are consecutively released upon one-by-one electron transfer
-
-
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SYSTEMATIC NAME
IUBMB Comments
CoB,CoM:ferredoxin oxidoreductase
HdrABC is an enzyme complex that is found in most methanogens and catalyses the reduction of the CoB-CoM heterodisulfide back to CoB and CoM. HdrA contains a FAD cofactor that acts as the entry point for electrons, which are transferred via HdrC to the HdrB catalytic subunit. One form of the enzyme from Methanosarcina acetivorans (HdrA2B2C2) can also catalyse EC 1.8.98.4, coenzyme F420:CoB-CoM heterodisulfide,ferredoxin reductase. cf. EC 1.8.98.5, H2:CoB-CoM heterodisulfide,ferredoxin reductase, EC 1.8.98.6, formate:CoB-CoM heterodisulfide,ferredoxin reductase, and EC 1.8.98.1, dihydromethanophenazine:CoB-CoM heterodisulfide reductase.
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SUBSTRATE
PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
(Substrate)
LITERATURE
(Substrate)
(Substrate)
COMMENTARY
(Product)
(Product)
LITERATURE
(Product)
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
2 reduced ferredoxin [iron-sulfur] cluster + CoB + CoM + 2 H+
2 H2 + 2 oxidized ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB
2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + H+
reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + H+
oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
reduced ferredoxin [iron-sulfur] cluster + DsrC-S-S-DsrC + H+
oxidized ferredoxin [iron-sulfur] cluster + DsrC + DsrC
2 reduced ferredoxin [iron-sulfur] cluster + CoB + CoM + 2 H+
2 H2 + 2 oxidized ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB
-
-
-
?
2 reduced ferredoxin [iron-sulfur] cluster + CoB + CoM + 2 H+
2 H2 + 2 oxidized ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB
-
-
-
?
2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
P60200; Q58153; Q58273; Q58154; Q58274
-
-
-
?
2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
P60200; Q58153; Q58273; Q58154; Q58274
-
-
-
?
2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
P60200; Q58153; Q58273; Q58154; Q58274
-
-
-
?
2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
P60200; Q58153; Q58273; Q58154; Q58274
-
-
-
?
2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
P60200; Q58153; Q58273; Q58154; Q58274
-
-
-
?
2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
P60200; Q58153; Q58273; Q58154; Q58274
-
-
-
?
2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
-
-
-
-
?
2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
-
-
-
?
2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
-
-
-
-
?
2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
-
-
-
?
2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
-
-
-
?
2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
-
-
-
?
2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
-
-
-
?
oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + H+
-
-
-
-
?
oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + H+
-
-
-
-
?
oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + H+
-
-
-
-
?
oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + H+
-
-
-
-
?
oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + H+
-
-
-
-
r
oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + H+
-
-
-
-
?
oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + H+
-
-
-
?
oxidized methyl viologen + CoB + CoM
reduced methyl viologen + CoM-S-S-CoB + H+
-
-
-
-
?
oxidized methyl viologen + CoB + CoM
reduced methyl viologen + CoM-S-S-CoB + H+
-
-
-
-
?
reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + H+
oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
-
-
-
-
?
reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + H+
oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
-
-
-
-
?
reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + H+
oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
-
-
-
-
r
reduced ferredoxin [iron-sulfur] cluster + DsrC-S-S-DsrC + H+
oxidized ferredoxin [iron-sulfur] cluster + DsrC + DsrC
-
-
-
-
?
reduced ferredoxin [iron-sulfur] cluster + DsrC-S-S-DsrC + H+
oxidized ferredoxin [iron-sulfur] cluster + DsrC + DsrC
-
-
-
-
?
additional information
?
-
-
thiols are only produced when membranes of Methanomassiliicoccus luminyensis, HdrD, Fd, and IOR are present. In the absence of Fd, HdrD, or washed membranes, thiol formation is very low indicating that all above-mentioned components are necessary for an effective electron transfer from Fdred to CoM-S-S-CoB. Fd:heterodisulfide reductase activity is measured by the oxidation of Fdred as the initial reaction and thiol formation by CoM-S-S-CoB reduction as a final reaction of the proposed electron transport chain. At least one membrane-bound enzyme is needed for electron transport
-
-
-
additional information
?
-
Hdr receives two electrons from the oxidation of H2 through MvhAGD [NiFe]-hydrogenase, cf. EC 1.8.98.4
-
-
-
additional information
?
-
heterodisulfide reductase (HdrABC) reduces the disulfide bond with electrons supplied from the oxidation of 2H2 or 2HCO2H catalyzed by F420-independent hydrogenase or Fdh. The exergonic reduction of CoMS-SCoB drives the endergonic reduction of CO2 in the first step via FBEB by HdrABC
-
-
-
additional information
?
-
Hdr receives two electrons from the oxidation of H2 through MvhAGD [NiFe]-hydrogenase, cf. EC 1.8.98.4
-
-
-
additional information
?
-
heterodisulfide reductase (HdrABC) reduces the disulfide bond with electrons supplied from the oxidation of 2H2 or 2HCO2H catalyzed by F420-independent hydrogenase or Fdh. The exergonic reduction of CoMS-SCoB drives the endergonic reduction of CO2 in the first step via FBEB by HdrABC
-
-
-
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NATURAL SUBSTRATE
NATURAL PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
(Substrate)
LITERATURE
(Substrate)
(Substrate)
COMMENTARY
(Product)
(Product)
LITERATURE
(Product)
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
2 reduced ferredoxin [iron-sulfur] cluster + CoB + CoM + 2 H+
2 H2 + 2 oxidized ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB
2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + H+
reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + H+
oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
reduced ferredoxin [iron-sulfur] cluster + DsrC-S-S-DsrC + H+
oxidized ferredoxin [iron-sulfur] cluster + DsrC + DsrC
2 reduced ferredoxin [iron-sulfur] cluster + CoB + CoM + 2 H+
2 H2 + 2 oxidized ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB
-
-
-
?
2 reduced ferredoxin [iron-sulfur] cluster + CoB + CoM + 2 H+
2 H2 + 2 oxidized ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB
-
-
-
?
2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
P60200; Q58153; Q58273; Q58154; Q58274
-
-
-
?
2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
P60200; Q58153; Q58273; Q58154; Q58274
-
-
-
?
2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
P60200; Q58153; Q58273; Q58154; Q58274
-
-
-
?
2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
P60200; Q58153; Q58273; Q58154; Q58274
-
-
-
?
2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
P60200; Q58153; Q58273; Q58154; Q58274
-
-
-
?
2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
P60200; Q58153; Q58273; Q58154; Q58274
-
-
-
?
2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
-
-
-
-
?
2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
-
-
-
?
2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
-
-
-
-
?
2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
-
-
-
?
2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
-
-
-
?
2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
-
-
-
?
2 reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + 2 H+
2 oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
-
-
-
?
oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + H+
-
-
-
-
?
oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + H+
-
-
-
-
?
oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + H+
-
-
-
-
?
oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + H+
-
-
-
-
?
oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + H+
-
-
-
-
r
oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + H+
-
-
-
-
?
oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + H+
-
-
-
?
reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + H+
oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
-
-
-
-
?
reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + H+
oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
-
-
-
-
?
reduced ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB + H+
oxidized ferredoxin [iron-sulfur] cluster + CoB + CoM
-
-
-
-
r
reduced ferredoxin [iron-sulfur] cluster + DsrC-S-S-DsrC + H+
oxidized ferredoxin [iron-sulfur] cluster + DsrC + DsrC
-
-
-
-
?
reduced ferredoxin [iron-sulfur] cluster + DsrC-S-S-DsrC + H+
oxidized ferredoxin [iron-sulfur] cluster + DsrC + DsrC
-
-
-
-
?
additional information
?
-
Hdr receives two electrons from the oxidation of H2 through MvhAGD [NiFe]-hydrogenase, cf. EC 1.8.98.4
-
-
-
additional information
?
-
Hdr receives two electrons from the oxidation of H2 through MvhAGD [NiFe]-hydrogenase, cf. EC 1.8.98.4
-
-
-
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COFACTOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
FAD
required for activity. Conformational changes within the HdrA subunit provide a conformationally gated pathway for electrons to and from the bifurcating flavin adenine dinucleotide (FAD)
FAD
the enzyme is an iron-sulfur subunit A of the HdrABC complex and contains [4 Fe-4S] clusters
FAD
-
the multisubunit enzyme complex is composed of a dimer of two HdrABC-MvhAGD heterohexamers with a flavin-containing HdrA dimer in the center, to which two catalytic arms, MvhAGD and HdrBC, are attached
FAD
the multisubunit enzyme complex is composed of a dimer of two HdrABC-MvhAGD heterohexamers with a flavin-containing HdrA dimer in the center, to which two catalytic arms, MvhAGD and HdrBC, are attached
FAD
P60200; Q58153; Q58273; Q58154; Q58274
the multisubunit enzyme complex is composed of a dimer of two HdrABC-MvhAGD heterohexamers with a flavin-containing HdrA dimer in the center, to which two catalytic arms, MvhAGD and HdrBC, are attached
Fe-S center
-
subunits HdrB of heterodisulfide reductase (HdrABC-MvhAGD) contains two noncubane [4Fe-4S] clusters used for reduction activity. The two noncubane [4Fe-4S] clusters are composed of fused [3Fe-4S]-[2Fe-2S] units sharing 1 iron (Fe) and 1 sulfur (S), which are coordinated at the CCG motifs. The N-terminal domain has a fold similar to MvhD but contains, instead of a [2Fe-2S] cluster, a [4Fe-4S] cluster (HA3) that is unusually ligated by five cysteines
Fe-S center
subunits HdrB of heterodisulfide reductase (HdrABC-MvhAGD) contains two noncubane [4Fe-4S] clusters used for reduction activity. The two noncubane [4Fe-4S] clusters are composed of fused [3Fe-4S]-[2Fe-2S] units sharing 1 iron (Fe) and 1 sulfur (S), which are coordinated at the CCG motifs. The N-terminal domain has a fold similar to MvhD but contains, instead of a [2Fe-2S] cluster, a [4Fe-4S] cluster (HA3) that is unusually ligated by five cysteines
Fe-S center
P60200; Q58153; Q58273; Q58154; Q58274
subunits HdrB of heterodisulfide reductase (HdrABC-MvhAGD) contains two noncubane [4Fe-4S] clusters used for reduction activity. The two noncubane [4Fe-4S] clusters are composed of fused [3Fe-4S]-[2Fe-2S] units sharing 1 iron and 1 sulfur, which are coordinated at the CCG motifs. The N-terminal domain has a fold similar to MvhD but contains, instead of a [2Fe-2S] cluster, a [4Fe-4S] cluster (HA3) that is unusually ligated by five cysteines
additional information
the enzyme contains (4Fe-4S)clusters
-
additional information
the HdrABC·MvhAGD (see also EC 1.8.98.1) complex is abundant in iron-sulfur cofactors, with 11 [4 Fe-4S] clusters, one [2 Fe-2S], a Ni-Fe site for H2 catalysis, and two noncubane iron-sulfur clusters
-
additional information
-
the thioredoxin reductase domain of HdrA (145 to 236 and 315 to 567) resembles thioredoxin reductase in the fold and geometry of the FAD-binding site but forms a completely different dimer interface, owing to the perpendicular position of the respective two-fold axes. The thioredoxin-reductase domain of HdrA has, in addition, a [4Fe-4S] cluster (HA4) that is surrounded by several basic residues and coordinated with a Cys386, Cys399, Cys403, and Cys404 sequence motif (consensus sequence CX10-16-Y/W/H/F-C-S/A/C-X2-3CC)
-
additional information
the thioredoxin reductase domain of HdrA (145 to 236 and 315 to 567) resembles thioredoxin reductase in the fold and geometry of the FAD-binding site but forms a completely different dimer interface, owing to the perpendicular position of the respective two-fold axes. The thioredoxin-reductase domain of HdrA has, in addition, a [4Fe-4S] cluster (HA4) that is surrounded by several basic residues and coordinated with a Cys386, Cys399, Cys403, and Cys404 sequence motif (consensus sequence CX10-16-Y/W/H/F-C-S/A/C-X2-3CC)
-
additional information
P60200; Q58153; Q58273; Q58154; Q58274
the thioredoxin reductase domain of HdrA (145 to 236 and 315 to 567) resembles thioredoxin reductase in the fold and geometry of the FAD-binding site but forms a completely different dimer interface, owing to the perpendicular position of the respective two-fold axes. The thioredoxin-reductase domain of HdrA has, in addition, a [4Fe-4S] cluster (HA4) that is surrounded by several basic residues and coordinated with a Cys386, Cys399, Cys403, and Cys404 sequence motif (consensus sequence CX10-16-Y/W/H/F-C-S/A/C-X2-3CC)
-
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METALS and IONS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
Fe2+
Zn2+
Fe2+
P60200; Q58153; Q58273; Q58154; Q58274
in two noncubane [4Fe-4S] clusters of HdrB. The two noncubane [4Fe-4S] clusters are composed of fused [3Fe-4S]-[2Fe-2S] units sharing 1 iron and 1 sulfur, which are coordinated at the CCG motifs
Fe2+
-
in two noncubane [4Fe-4S] clusters of HdrB. The two noncubane [4Fe-4S] clusters are composed of fused [3Fe-4S]-[2Fe-2S] units sharing 1 iron and 1 sulfur, which are coordinated at the CCG motifs
Fe2+
in two noncubane [4Fe-4S] clusters of HdrB. The two noncubane [4Fe-4S] clusters are composed of fused [3Fe-4S]-[2Fe-2S] units sharing 1 iron and 1 sulfur, which are coordinated at the CCG motifs
Fe2+
the enzyme is an iron-sulfur subunit A of the HdrABC complex and contains [4 Fe-4S] clusters
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KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
0.05
CoM-S-S-CoB
-
subunit HdrB2C2, at 21°C, pH not specified in the publication
1.1
CoB
-
subunit HdrB2, at 21°C, pH not specified in the publication
1.2
CoB
-
subunit HdrB2C2, at 21°C, pH not specified in the publication
1.2
CoM
-
subunit HdrB2, at 21°C, pH not specified in the publication
1.4
CoM
-
subunit HdrB2C2, at 21°C, pH not specified in the publication
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ORGANISM
COMMENTARY
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
CoB-CoM heterodisulfide reductase subunits A, B1, B2, C1, and C2; Methanococcus jannaschii
P60200; Q58153; Q58273; Q58154; Q58274
UniProt
brenda
CoB-CoM heterodisulfide reductase subunits A, B1, B2, C1, and C2; Methanococcus jannaschii
P60200; Q58153; Q58273; Q58154; Q58274
UniProt
brenda
CoB-CoM heterodisulfide reductase subunits A, B1, B2, C1, and C2; Methanococcus jannaschii
P60200; Q58153; Q58273; Q58154; Q58274
UniProt
brenda
CoB-CoM heterodisulfide reductase subunits A, B1, B2, C1, and C2; Methanococcus jannaschii
P60200; Q58153; Q58273; Q58154; Q58274
UniProt
brenda
CoB-CoM heterodisulfide reductase subunits A, B1, B2, C1, and C2; Methanococcus jannaschii
P60200; Q58153; Q58273; Q58154; Q58274
UniProt
brenda
CoB-CoM heterodisulfide reductase subunits A, B1, B2, C1, and C2; Methanococcus jannaschii
P60200; Q58153; Q58273; Q58154; Q58274
UniProt
brenda
CoB-CoM heterodisulfide reductase iron-sulfur subunit A
UniProt
brenda
CoB-CoM heterodisulfide reductase subunits A, B, and C
UniProt
brenda
CoB-CoM heterodisulfide reductase iron-sulfur subunit A
UniProt
brenda
CoB-CoM heterodisulfide reductase subunits A, B, and C
UniProt
brenda
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LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY
GeneOntology No.
LITERATURE
SOURCE
-
brenda
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GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
evolution
metabolism
physiological function
additional information
evolution
conservation of Hdr and Fmd structures suggests that the complex of both is common among hydrogenotrophic methanogens
evolution
-
HdrA homologues are found in many other microorganisms, i.e. anaerobic methanotrophic archaea, sulfate-reducing bacteria and archaea, sulfur-oxidizing bacteria, acetogenic bacteria, knallgas bacteria, and metal-reducing bacteria
evolution
HdrA homologues are found in many other microorganisms, i.e. anaerobic methanotrophic archaea, sulfate-reducing bacteria and archaea, sulfur-oxidizing bacteria, acetogenic bacteria, knallgas bacteria, and metal-reducing bacteria. The fifth cysteine Cys197' of Methanothermococcus thermolithotrophicus HdrA is exchanged for a selenocysteine in HdrA from Methanocaldococcus jannaschii
evolution
P60200; Q58153; Q58273; Q58154; Q58274
HdrA homologues are found in many other microorganisms, i.e. anaerobic methanotrophic archaea, sulfate-reducing bacteria and archaea, sulfur-oxidizing bacteria, acetogenic bacteria, knallgas bacteria, and metal-reducing bacteria. The fifth cysteine Cys197' of Methanothermococcus thermolithotrophicus HdrA is exchanged for a selenocysteine in HdrA from Methanocaldococcus jannaschii
evolution
-
the energy-conserving system in Methanomassiliicoccus luminyensis is unique, and the enzymes involved in this process are not found in this combination in members of the other methanogenic orders. The composition of the enzymes involved in ion translocation across the cytoplasmic membrane is different from all other methanogenic archaea
evolution
-
HdrA homologues are found in many other microorganisms, i.e. anaerobic methanotrophic archaea, sulfate-reducing bacteria and archaea, sulfur-oxidizing bacteria, acetogenic bacteria, knallgas bacteria, and metal-reducing bacteria. The fifth cysteine Cys197' of Methanothermococcus thermolithotrophicus HdrA is exchanged for a selenocysteine in HdrA from Methanocaldococcus jannaschii
-
evolution
-
HdrA homologues are found in many other microorganisms, i.e. anaerobic methanotrophic archaea, sulfate-reducing bacteria and archaea, sulfur-oxidizing bacteria, acetogenic bacteria, knallgas bacteria, and metal-reducing bacteria. The fifth cysteine Cys197' of Methanothermococcus thermolithotrophicus HdrA is exchanged for a selenocysteine in HdrA from Methanocaldococcus jannaschii
-
evolution
-
HdrA homologues are found in many other microorganisms, i.e. anaerobic methanotrophic archaea, sulfate-reducing bacteria and archaea, sulfur-oxidizing bacteria, acetogenic bacteria, knallgas bacteria, and metal-reducing bacteria. The fifth cysteine Cys197' of Methanothermococcus thermolithotrophicus HdrA is exchanged for a selenocysteine in HdrA from Methanocaldococcus jannaschii
-
evolution
-
HdrA homologues are found in many other microorganisms, i.e. anaerobic methanotrophic archaea, sulfate-reducing bacteria and archaea, sulfur-oxidizing bacteria, acetogenic bacteria, knallgas bacteria, and metal-reducing bacteria. The fifth cysteine Cys197' of Methanothermococcus thermolithotrophicus HdrA is exchanged for a selenocysteine in HdrA from Methanocaldococcus jannaschii
-
evolution
-
HdrA homologues are found in many other microorganisms, i.e. anaerobic methanotrophic archaea, sulfate-reducing bacteria and archaea, sulfur-oxidizing bacteria, acetogenic bacteria, knallgas bacteria, and metal-reducing bacteria. The fifth cysteine Cys197' of Methanothermococcus thermolithotrophicus HdrA is exchanged for a selenocysteine in HdrA from Methanocaldococcus jannaschii
-
evolution
-
HdrA homologues are found in many other microorganisms, i.e. anaerobic methanotrophic archaea, sulfate-reducing bacteria and archaea, sulfur-oxidizing bacteria, acetogenic bacteria, knallgas bacteria, and metal-reducing bacteria. The fifth cysteine Cys197' of Methanothermococcus thermolithotrophicus HdrA is exchanged for a selenocysteine in HdrA from Methanocaldococcus jannaschii
-
metabolism
a methyl-CoM reductase catalyzes the reductive resolution of methyl-CoM to form methane and a disulfide CoM conjugate of coenzyme B (CoM-S-S-CoB). This is the penultimate conserved step in all pathways of methanogenesis leaving only the reduction of CoM-S-S-CoB and recycling of the key methanogen cofactors CoM and CoB.. The reduction of CoM-S-S-CoB is often coupled to the oxidation of H2, an exergonic reaction with a significant negative free-energy change. Methanogens conserve the free energy by coupling this exergonic reaction to the hydrogen-dependent reduction of ferredoxin, which on its own would be an endergonic reaction. These reactions are coupled through flavin-based electron bifurcation that maximizes the energy efficiency in hydrogenotrophic methanogenesis. Heterodisulfide reductase (Hdr) is the valve that closes the cycle of methanogenesis, allowing energy to be conserved and providing an energetic advantage to the cell. Hdr catalyzes flavin-based electron bifurcation that results in the exergonic reduction of heterodisulfide (CoMS-S-CoB) coupled to the endergonic reduction of ferredoxin. In the proposed mechanism of bifurcation, the bifurcation-site flavin receives two electrons from a single donor, and then bifurcate one electron to reduce the heterodisulfide and one electron to reduce ferredoxin. Another round of bifurcation results in the complete reduction of CoM-S-S-CoB to HS-CoB and HS-CoM and 2 equivalents of reduced ferredoxin. Hdr receives two electrons from the oxidation of H2 through MvhAGD [NiFe]-hydrogenase EC 1.8.98.4
metabolism
-
in methanogenic archaea, the carbon dioxide (CO2) fixation and methane-forming steps are linked through the heterodisulfide reductase (HdrABC)-[NiFe]-hydrogenase (MvhAGD) complex that uses flavin-based electron bifurcation to reduce ferredoxin and the heterodisulfide of coenzymes M and B
metabolism
in methanogenic archaea, the carbon dioxide (CO2) fixation and methane-forming steps are linked through the heterodisulfide reductase (HdrABC)-[NiFe]-hydrogenase (MvhAGD) complex that uses flavin-based electron bifurcation to reduce ferredoxin and the heterodisulfide of coenzymes M and B
metabolism
P60200; Q58153; Q58273; Q58154; Q58274
in methanogenic archaea, the carbon dioxide (CO2) fixation and methane-forming steps are linked through the heterodisulfide reductase (HdrABC)-[NiFe]-hydrogenase (MvhAGD) complex that uses flavin-based electron bifurcation to reduce ferredoxin and the heterodisulfide of coenzymes M and B
metabolism
reduction of the disulfide of coenzyme M and coenzyme B (CoMS-SCoB) by heterodisulfide reductases (HdrED and HdrABC) is the final step in all methanogenic pathways. Flavin-based electron bifurcation (FBEB) by soluble HdrABC homologues play additional roles in driving essential endergonic reactions at the expense of the exergonic reduction of CoMS-SCoM. In the first step of the CO2 reduction pathway, HdrABC complexed with hydrogenase (EC 1.12.1.2) or formate dehydrogenase generates reduces ferredoxin (Fdx2-) for the endergonic reduction of CO2 coupled to the exergonic reduction of CoMS-SCoB dependent on FBEB of electrons from H2 or formate, respectively. Roles for HdrABC:hydrogenase complexes are also proposed for pathways wherein the methyl group of methanol is reduced to methane with electrons from H2. The HdrABC complexes catalyze FBEB-dependent oxidation of H2 for the endergonic reduction of Fdx driven by the exergonic reduction of CoMS-SCoB. The Fdx2- supplies electrons for reduction of the methyl group to methane. In H2- independent pathways, threefourths of the methyl groups are oxidized producing Fdx2- and reduced coenzyme F420 (F420H2). The F420H2 donates electrons for reduction of the remaining methyl groups to methane requiring transfer of electrons from Fdx2- to F420. HdrA1B1C1 is proposed to catalyze FBEB-dependent oxidation of Fdx2- for the endergonic reduction of F420 driven by the exergonic reduction of CoMS-SCoB, see for EC 1.8.98.4. In H2- independent acetotrophic pathways (EC 1.8.98.5), the methyl group of acetate is reduced to methane with electrons derived from oxidation of the carbonyl group mediated by Fdx. Electron transport involves a membrane-bound complex (Rnf) that oxidizes Fdx2- and generates a NaC gradient driving ATP synthesis. It is postulated that F420 is reduced by Rnf requiring HdrA2B2C2 catalyzing FBEB-dependent oxidation of F420H2 for the endergonic reduction of Fdx driven by the exergonic reduction of CoMS-SCoB (EC 1.8.98.4). The Fdx2- is recycled by Rnf and HdrA2B2C2 thereby conserving energy. The HdrA2B2C2 is also proposed to play a role in Fe(III)-dependent reverse methanogenesis. A flavin-based electron confurcating (FBEC) HdrABC complex is proposed for nitrate-dependent reverse methanogenesis in which the oxidation of CoM-SH/CoB-SH and Fdx2- is coupled to reduction of F420. The F420H2 donates electrons to a membrane complex that generates a proton gradient driving ATP synthesis
metabolism
the first reaction of the methanogenic pathway from carbon dioxide (CO2) is the reduction and condensation of CO2 to formyl-methanofuran, catalyzed by formyl-methanofuran dehydrogenase (Fmd, EC 1.12.7.2). Strongly reducing electrons for this reaction are generated by heterodisulfide reductase (Hdr, EC 1.8.7.3) in complex with hydrogenase or formate dehydrogenase (Fdh) using a flavin-based electron-bifurcation mechanism
metabolism
-
the process of methanogenesis in Methanomassiliicoccus luminyensis involves the transfer of methyl group from methanol or methylamines to 2-mercaptoethanesulfonate (HSCoM). The resulting methyl-S-CoM is reduced to methane by the methyl-CoM reductase which uses 7-mercaptoheptanoylthreonine phosphate (HS-CoB) as a reductant and forms the heterodisulfide (CoM-S-SCoB). The membrane-bound electron transport is based on the headless Fpo complex, which accepts electrons from Fdred and channels these electrons to the heterodisulfide reductase HdrD. And HdrD reduces the final electron acceptor the heterodisulfide (CoB-S-S-CoM)
metabolism
-
in methanogenic archaea, the carbon dioxide (CO2) fixation and methane-forming steps are linked through the heterodisulfide reductase (HdrABC)-[NiFe]-hydrogenase (MvhAGD) complex that uses flavin-based electron bifurcation to reduce ferredoxin and the heterodisulfide of coenzymes M and B
-
metabolism
-
in methanogenic archaea, the carbon dioxide (CO2) fixation and methane-forming steps are linked through the heterodisulfide reductase (HdrABC)-[NiFe]-hydrogenase (MvhAGD) complex that uses flavin-based electron bifurcation to reduce ferredoxin and the heterodisulfide of coenzymes M and B
-
metabolism
-
in methanogenic archaea, the carbon dioxide (CO2) fixation and methane-forming steps are linked through the heterodisulfide reductase (HdrABC)-[NiFe]-hydrogenase (MvhAGD) complex that uses flavin-based electron bifurcation to reduce ferredoxin and the heterodisulfide of coenzymes M and B
-
metabolism
-
in methanogenic archaea, the carbon dioxide (CO2) fixation and methane-forming steps are linked through the heterodisulfide reductase (HdrABC)-[NiFe]-hydrogenase (MvhAGD) complex that uses flavin-based electron bifurcation to reduce ferredoxin and the heterodisulfide of coenzymes M and B
-
metabolism
-
a methyl-CoM reductase catalyzes the reductive resolution of methyl-CoM to form methane and a disulfide CoM conjugate of coenzyme B (CoM-S-S-CoB). This is the penultimate conserved step in all pathways of methanogenesis leaving only the reduction of CoM-S-S-CoB and recycling of the key methanogen cofactors CoM and CoB.. The reduction of CoM-S-S-CoB is often coupled to the oxidation of H2, an exergonic reaction with a significant negative free-energy change. Methanogens conserve the free energy by coupling this exergonic reaction to the hydrogen-dependent reduction of ferredoxin, which on its own would be an endergonic reaction. These reactions are coupled through flavin-based electron bifurcation that maximizes the energy efficiency in hydrogenotrophic methanogenesis. Heterodisulfide reductase (Hdr) is the valve that closes the cycle of methanogenesis, allowing energy to be conserved and providing an energetic advantage to the cell. Hdr catalyzes flavin-based electron bifurcation that results in the exergonic reduction of heterodisulfide (CoMS-S-CoB) coupled to the endergonic reduction of ferredoxin. In the proposed mechanism of bifurcation, the bifurcation-site flavin receives two electrons from a single donor, and then bifurcate one electron to reduce the heterodisulfide and one electron to reduce ferredoxin. Another round of bifurcation results in the complete reduction of CoM-S-S-CoB to HS-CoB and HS-CoM and 2 equivalents of reduced ferredoxin. Hdr receives two electrons from the oxidation of H2 through MvhAGD [NiFe]-hydrogenase EC 1.8.98.4
-
metabolism
-
reduction of the disulfide of coenzyme M and coenzyme B (CoMS-SCoB) by heterodisulfide reductases (HdrED and HdrABC) is the final step in all methanogenic pathways. Flavin-based electron bifurcation (FBEB) by soluble HdrABC homologues play additional roles in driving essential endergonic reactions at the expense of the exergonic reduction of CoMS-SCoM. In the first step of the CO2 reduction pathway, HdrABC complexed with hydrogenase (EC 1.12.1.2) or formate dehydrogenase generates reduces ferredoxin (Fdx2-) for the endergonic reduction of CO2 coupled to the exergonic reduction of CoMS-SCoB dependent on FBEB of electrons from H2 or formate, respectively. Roles for HdrABC:hydrogenase complexes are also proposed for pathways wherein the methyl group of methanol is reduced to methane with electrons from H2. The HdrABC complexes catalyze FBEB-dependent oxidation of H2 for the endergonic reduction of Fdx driven by the exergonic reduction of CoMS-SCoB. The Fdx2- supplies electrons for reduction of the methyl group to methane. In H2- independent pathways, threefourths of the methyl groups are oxidized producing Fdx2- and reduced coenzyme F420 (F420H2). The F420H2 donates electrons for reduction of the remaining methyl groups to methane requiring transfer of electrons from Fdx2- to F420. HdrA1B1C1 is proposed to catalyze FBEB-dependent oxidation of Fdx2- for the endergonic reduction of F420 driven by the exergonic reduction of CoMS-SCoB, see for EC 1.8.98.4. In H2- independent acetotrophic pathways (EC 1.8.98.5), the methyl group of acetate is reduced to methane with electrons derived from oxidation of the carbonyl group mediated by Fdx. Electron transport involves a membrane-bound complex (Rnf) that oxidizes Fdx2- and generates a NaC gradient driving ATP synthesis. It is postulated that F420 is reduced by Rnf requiring HdrA2B2C2 catalyzing FBEB-dependent oxidation of F420H2 for the endergonic reduction of Fdx driven by the exergonic reduction of CoMS-SCoB (EC 1.8.98.4). The Fdx2- is recycled by Rnf and HdrA2B2C2 thereby conserving energy. The HdrA2B2C2 is also proposed to play a role in Fe(III)-dependent reverse methanogenesis. A flavin-based electron confurcating (FBEC) HdrABC complex is proposed for nitrate-dependent reverse methanogenesis in which the oxidation of CoM-SH/CoB-SH and Fdx2- is coupled to reduction of F420. The F420H2 donates electrons to a membrane complex that generates a proton gradient driving ATP synthesis
-
metabolism
-
in methanogenic archaea, the carbon dioxide (CO2) fixation and methane-forming steps are linked through the heterodisulfide reductase (HdrABC)-[NiFe]-hydrogenase (MvhAGD) complex that uses flavin-based electron bifurcation to reduce ferredoxin and the heterodisulfide of coenzymes M and B
-
metabolism
-
in methanogenic archaea, the carbon dioxide (CO2) fixation and methane-forming steps are linked through the heterodisulfide reductase (HdrABC)-[NiFe]-hydrogenase (MvhAGD) complex that uses flavin-based electron bifurcation to reduce ferredoxin and the heterodisulfide of coenzymes M and B
-
physiological function
-
energy conservation in the gut microbe Methanomassiliicoccus luminyensis is based on membrane-bound ferredoxin oxidation coupled to heterodisulfide reduction. Energy transduction is dependent on a membrane-bound ferredoxin:heterodisulfide oxidoreductase composed of reduced ferredoxin as an electron donor, at least one protein in the membrane fraction and the heterodisulfide reductase HdrD, which reduces the electron acceptor CoMS-S-CoB. Electron transfer of this respiratory chain proceeds with a rate of 145 nmol reduced heterodisulfide per min/mg membrane protein. Only protons are used as coupling ions for the generation of the electrochemical ion gradient. The membrane-bound F420H2:phenazine oxidoreductase complex (without the electron input module FpoF) probably catalyzes the oxidati