Methyl‐Coenzyme M Reductase and its Nickel Corphin Coenzyme F
            <sub>430</sub>
            in Methanogenic Archaea

Jaun, Bernhard; Thauer, Rudolf K.

doi:10.1002/9780470028131.ch8

Cited by 29 publications

(38 citation statements)

References 109 publications

(204 reference statements)

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“…Oxidation-driven reduction reactions are not without precedent. In the bc 1 complex of the respiratory chain the oxidation of reduced ubiquinone by cytochrome c drives the reduction of cytochrome b (5,17,30), in ribonucleotide reductases the oxidation of a cysteine thiol to a thiyl radical drives the reduction of ribonucleotides to deoxyribonucleotides (28,29,45), and in methyl-CoM reductase the oxidation of the thiol group of CoM or CoB to the thiyl radical drives the rereduction of the nickel tetrapyrrole from the Ni(II) state to the Ni(I) state (18,47). In all these cases an endergonic one-electron reduction step is coupled to an exergonic one-electron oxidation step involving radical intermediates which have to be stabilized in the enzyme.…”

Section: Discussionmentioning

confidence: 99%

Coupled Ferredoxin and Crotonyl Coenzyme A (CoA) Reduction with NADH Catalyzed by the Butyryl-CoA Dehydrogenase/Etf Complex from Clostridium kluyveri

et al. 2008

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Cell extracts of butyrate-forming clostridia have been shown to catalyze acetyl-coenzyme A (acetyl-CoA)-and ferredoxin-dependent formation of H 2 from NADH. It has been proposed that these bacteria contain an NADH:ferredoxin oxidoreductase which is allosterically regulated by acetyl-CoA. We report here that ferredoxin reduction with NADH in cell extracts from Clostridium kluyveri is catalyzed by the butyryl-CoA dehydrogenase/Etf complex and that the acetyl-CoA dependence previously observed is due to the fact that the cell extracts catalyze the reduction of acetyl-CoA with NADH via crotonyl-CoA to butyryl-CoA. The cytoplasmic butyryl-CoA dehydrogenase complex was purified and is shown to couple the endergonic reduction of ferredoxin (E 0 ‫؍‬ ؊410 mV) with NADH (E 0 ‫؍‬ ؊320 mV) to the exergonic reduction of crotonyl-CoA to butyryl-CoA (E 0 ‫؍‬ ؊10 mV) with NADH. The stoichiometry of the fully coupled reaction is extrapolated to be as follows: 2 NADH ؉ 1 oxidized ferredoxin ؉ 1 crotonyl-CoA ‫؍‬ 2 NAD ؉ ؉ 1 ferredoxin reduced by two electrons ؉ 1 butyryl-CoA. The implications of this finding for the energy metabolism of butyrate-forming anaerobes are discussed in the accompanying paper.Clostridium kluyveri is a strictly anaerobic gram-positive endospore-forming bacterium (2). Among the clostridia this organism is unique in fermenting ethanol and acetate to butyrate, caproate, and H 2 (38, 49) and in deriving a large portion (30%) of its cell carbon from CO 2 (52). Both its energy metabolism and its pathways of biosynthesis have therefore been the subject of many investigations (26, 39a). In particular, understanding the energy metabolism of C. kluyveri remains a challenge for microbiologists, and one of the pertinent questions is how this organism generates H 2 (36, 39a, 48).

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Section: Discussionmentioning

confidence: 99%

Coupled Ferredoxin and Crotonyl Coenzyme A (CoA) Reduction with NADH Catalyzed by the Butyryl-CoA Dehydrogenase/Etf Complex from Clostridium kluyveri

et al. 2008

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“…Three mechanisms for MCR are currently considered 44,54 . In mechanism 1 the methyl group of methyl‐coenzyme M reacts with the Ni(I) in a nucleophilic substitution reaction, yielding methyl‐Ni(III) and coenzyme M, which in turn react to methyl‐Ni(II) and the thiyl radical of coenzyme M. Methyl‐Ni(II) then reacts with a proton in an electrophilic substitution reaction to methane and Ni(II), and the coenzyme M thiyl radical reacts with coenzyme B, yielding a disulfide anion radical, which is a strong reductant and which reduces Ni(II) back to Ni(I), thus closing the catalytic cycle.…”

Section: Anaerobic Oxidation Of Methane With Sulfatementioning

confidence: 99%

“…Due to the negative redox potential, which is more than 0.2 V below that of the hydrogen electrode at pH 7.0, and due to the fact that in the enzyme F 430 is not completely electrically insulated from electron acceptors present in the solvent, Ni(I)F 430 in MCR slowly oxidizes to Ni(II)F 430 , even under strictly anoxic conditions. The rate of MCR inactivation increases with increasing redox potetial in its environment 44 . Considering that re‐reduction of MCR in the cells requires ATP, 54 the negative redox potential of F 430 could preclude the operation of MCR in cells, in which the redox potential of the terminal electron acceptors is more positive than 0 V as in the case of the nitrate/nitrite couple (E°′ = +0.43 V), the NO 2 − /NO couple (E°′ = +0.34 V), the NO/N 2 O couple (E°′ = +1.17 V), and the N 2 O/N 2 couple (E°′ = +1.36 V).…”

Section: Anaerobic Oxidation Of Methane With Nitratementioning

confidence: 99%

Methane as Fuel for Anaerobic Microorganisms

Thauer

Shima

2008

Annals of the New York Academy of Sciences

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Methane has long been known to be used as a carbon and energy source by some aerobic alpha- and delta-proteobacteria. In these organisms the metabolism of methane starts with its oxidation with O(2) to methanol, a reaction catalyzed by a monooxygenase and therefore restricted to the aerobic world. Methane has recently been shown to also fuel the growth of anaerobic microorganisms. The oxidation of methane with sulfate and with nitrate have been reported, but the mechanisms of anaerobic methane oxidation still remains elusive. Sulfate-dependent methane oxidation is catalyzed by methanotrophic archaea, which are related to the Methanosarcinales and which grow in close association with sulfate-reducing delta-proteobacteria. There is evidence that anaerobic methane oxidation with sulfate proceeds at least in part via reversed methanogenesis involving the nickel enzyme methyl-coenzyme M reductase for methane activation, which under standard conditions is an endergonic reaction, and thus inherently slow. Methane oxidation coupled to denitrification is mediated by bacteria belonging to a novel phylum and does not involve methyl-coenzyme M reductase. The first step in methane oxidation is most likely the exergonic formation of 2-methylsuccinate from fumarate and methane catalyzed by a glycine-radical enzyme.

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“…1 Further motivation for detailed studies of the structure and function of ACS derive from a desire to understand the novel cofactors utilized by archaea and their ability to promote one-carbon transformations via the proposed intermediacy of unprecedented organometallic species in biology, including Ni-CO, Ni-CH 3 and Ni-C(O)CH 3 adducts. 4 …”

Section: Introductionmentioning

confidence: 99%

Synthetic analogs for evaluating the influence of N–H⋯S hydrogen bonds on the formation of thioester in acetyl coenzyme a synthase

et al. 2009

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A series of square planar methylnickel(II) complexes, (dppe)Ni(Me)(SAr) (dppe = 1,2-bis(diphenylphosphino)ethane); 2. Ar = phenyl; 3. Ar = pentafluorophenyl; 4. Ar = o-pivaloylaminophenyl; 5. Ar = p-pivaloylaminophenyl; (depe)Ni(Me)(SAr), (depe = 1,2-bis(diethylphosphino)ethane); 7. Ar = phenyl; 8. Ar = pentafluorophenyl; 9. Ar = o-pivaloylaminophenyl; 10. Ar = p-pivaloylaminophenyl), were synthesized via the reaction of (dppe)NiMe2(1) and (depe)NiMe2(6) with either the corresponding thiol or disulfide. These complexes were characterized by various spectroscopic methods including 31P NMR, 1H NMR, 13C NMR and infrared spectroscopies and in most cases by X-ray diffraction analyses. Solid state and solution measurements establish that 5 and 9 contain intramolecular N-H---S bonds. Carbonylation of the complexes 2-4, 7-10 leads to (dRpe)Ni(CO)2 and MeC(O)SAr via the intermediacy of the acylnickel adducts, (dRpe)Ni(C(O)Me)(SAr), detected at low temperature by 31P NMR spectroscopy. Consistent with experimental observations, density functional theory results reveal that the intramolecular hydrogen bond in 9 stabilizes the acylnickel adduct compared with its non-hydrogen-bonded adduct, 10. Oxidative addition of MeC(O)SC6F5 to (dRpe)Ni(COD) followed by spontaneous decarbonylation proceeds in modest yields generating 3 and 8.

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Methyl‐Coenzyme M Reductase and its Nickel Corphin Coenzyme F ₄₃₀ in Methanogenic Archaea

Cited by 29 publications

References 109 publications

Coupled Ferredoxin and Crotonyl Coenzyme A (CoA) Reduction with NADH Catalyzed by the Butyryl-CoA Dehydrogenase/Etf Complex from Clostridium kluyveri

Coupled Ferredoxin and Crotonyl Coenzyme A (CoA) Reduction with NADH Catalyzed by the Butyryl-CoA Dehydrogenase/Etf Complex from Clostridium kluyveri

Methane as Fuel for Anaerobic Microorganisms

Synthetic analogs for evaluating the influence of N–H⋯S hydrogen bonds on the formation of thioester in acetyl coenzyme a synthase

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Methyl‐Coenzyme M Reductase and its Nickel Corphin Coenzyme F 430 in Methanogenic Archaea

Cited by 29 publications

References 109 publications

Coupled Ferredoxin and Crotonyl Coenzyme A (CoA) Reduction with NADH Catalyzed by the Butyryl-CoA Dehydrogenase/Etf Complex from Clostridium kluyveri

Coupled Ferredoxin and Crotonyl Coenzyme A (CoA) Reduction with NADH Catalyzed by the Butyryl-CoA Dehydrogenase/Etf Complex from Clostridium kluyveri

Methane as Fuel for Anaerobic Microorganisms

Synthetic analogs for evaluating the influence of N–H⋯S hydrogen bonds on the formation of thioester in acetyl coenzyme a synthase

Contact Info

Product

Resources

About

Methyl‐Coenzyme M Reductase and its Nickel Corphin Coenzyme F ₄₃₀ in Methanogenic Archaea