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Literature summary for 1.8.98.4 extracted from

  • Yan, Z.; Ferry, J.
    Electron bifurcation and confurcation in methanogenesis and reverse methanogenesis (2018), Front. Microbiol., 9, 1322 .
    View publication on PubMedView publication on EuropePMC

Natural Substrates/ Products (Substrates)

Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
2 oxidized coenzyme F420 + 2 reduced ferredoxin [iron-sulfur] cluster + CoB + CoM + 2 H+ Methanosarcina acetivorans
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2 reduced coenzyme F420 + 2 oxidized ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB
-
?

Organism

Organism UniProt Comment Textmining
Methanosarcina acetivorans
-
-
-

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
2 oxidized coenzyme F420 + 2 reduced ferredoxin [iron-sulfur] cluster + CoB + CoM + 2 H+
-
Methanosarcina acetivorans 2 reduced coenzyme F420 + 2 oxidized ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB
-
?

Synonyms

Synonyms Comment Organism
hdrA2B2C2
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Methanosarcina acetivorans

Cofactor

Cofactor Comment Organism Structure
coenzyme F420
-
Methanosarcina acetivorans
Ferredoxin
-
Methanosarcina acetivorans

General Information

General Information Comment Organism
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 or formate dehydrogenase generates reduced 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. 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, three-fourths 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. When switched from growth with methanol to growth with acetate, Methanosarcina acetivorans upregulates an electron bifurcating heterodisulfide reductase (HdrA2B2C2) that oxidizes F420H2 and reduces Fdx driven by reduction of CoMS-SCoB. A role has been proposed for sHdrA2B2C2 dependent on reduction of NAD-like coenzyme F420 (F420) by the Rnf complex analogous to Fdx-dependent reduction of NADC by homologous Rnf complexes from the domain Bacteria. In this way, Fdx reduced by HdrA2B2C2 is re-oxidized by Rnf thereby supplementing the translocation of Na+. HdrA2B2C2 is involved in reverse methanogenesis Methanosarcina acetivorans
physiological function 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, three-fourths 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. When switched from growth with methanol to growth with acetate, Methanosarcina acetivorans upregulates an electron bifurcating heterodisulfide reductase (HdrA2B2C2) that oxidizes F420H2 and reduces Fdx driven by reduction of CoMS-SCoB. A role has been proposed for HdrA2B2C2 dependent on reduction of NAD-like coenzyme F420 (F420) by the Rnf complex analogous to Fdx-dependent reduction of NADC by homologous Rnf complexes from the domain Bacteria Methanosarcina acetivorans