Levels of coenzyme F420, coenzyme M, hydrogenase, and methylcoenzyme M methylreductase in acetate-grown Methanosarcina

Baresi, Larry; Wolfe, R. S.

doi:10.1128/aem.41.2.388-391.1981

Cited by 38 publications

(17 citation statements)

References 17 publications

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“…Evidence for a role in acetate conversion to CH 4 is reported for M. barkeri and M. thermophila. [56][57][58][59] The homodimeric enzyme from CO 2reducing methanogens has been extensively characterized. The crystal structure reveals two independent active sites containing the nickel-containing cofactor F 430 , which accepts the methyl group from CH 3 -S-CoM for reduction to CH 4 .…”

Section: Ch 3 -S-com + Hs-cobmentioning

confidence: 99%

Methanogenesis in Marine Sediments

Ferry

Lessner

2008

Annals of the New York Academy of Sciences

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The anaerobic conversion of complex organic matter to CH(4) is an essential link in the global carbon cycle. In freshwater anaerobic environments, the organic matter is decomposed to CH(4) and CO(2) by a microbial food chain that terminates with methanogens that produce methane primarily by reduction of the methyl group of acetate and also reduction of CO(2). The process also occurs in marine environments, particularly those receiving large loads of organic matter, such as coastal sediments. The great majority of research on methanogens has focused on marine and freshwater CO(2)-reducing species, and freshwater acetate-utilizing species. Recent molecular, biochemical, bioinformatic, proteomic, and microarray analyses of the marine isolate Methanosarcina acetivorans has revealed that the pathway for acetate conversion to methane differs significantly from that in freshwater methanogens. Similar experimental approaches have also revealed striking contrasts with freshwater species for the pathway of CO-dependent CO(2) reduction to methane by M. acetivorans. The differences in both pathways reflect an adaptation by M. acetivorans to the marine environment.

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Section: Ch 3 -S-com + Hs-cobmentioning

confidence: 99%

Methanogenesis in Marine Sediments

Ferry

Lessner

2008

Annals of the New York Academy of Sciences

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“…We also demonstrate that the hydrogenase enzyme activity levels are discretely regulated in relation to growth substrate. M. barkeri and other Methanosarcina species, Methanosarcina acetovorum and strain TM-1 synthesize hydrogenase during growth on acetate (manuscript in preparation) [21,22]. Since these methanogens also consume hydrogen with reduction of carbon dioxide or methanol [21,23,24], the hydrogenase enzyme complex could be constitutive, irrespective of the substrate, though regulation and control of various hydrogenase activity levels could be very complex and different on various growth substrates.…”

Section: Discussionmentioning

confidence: 99%

Analysis of hydrogen metabolism in Methanosarcina barkeri: Regulation of hydrogenase and role of CO-dehydrogenase in H2 production

Bhatnagar¹,

Krzycki²,

Zeikus³

1987

FEMS Microbiology Letters

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Methanosarcina barkeri strain MS had significant levels of in vivo hydrogenase activity and both produced and consumed hydrogen when grown on CO or methanol as sole carbon and energy source. The activities of multiple hydrogenases were detected in extracts and cells of M. barkeri grown on CO or methanol. Uptake hydrogenase activity was 4 times higher and production hydrogenase was 3 times lower in methanol than in CO‐grown cells. When 2‐bromoethane sulfonate was added to M. barkeri growing on methanol, methane production was inhibited while hydrogen was produced but not consumed, indicating that hydrogen may be an intermediate in methane production from methanol. CO inhibited in vivo hydrogenase activity of M. barkeri cells suggesting that CO might inhibit uptake hydrogenase activity and not production hydrogenase activity. Purified CO‐dehydrogenase (CODH) from M. barkeri produced 278.9 nmol hydrogen min−1· mg−1 protein using methyl viologen as electron carrier. Purified CODH did not display either detectable uptake hydrogenase activity or significant tritium exchange activity. Notably, 20 μM KCN inhibited both hydrogen producing and CO‐oxidizing activity of purified CODH, but not uptake hydrogenase activity. Thus, we propose that in addition to its role in acetate synthesis and degradation, CODH produces hydrogen as a by‐product of carbonyl group transformation.

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“…Hydrogenase, however, is a constitutive enzyme: activity did not vary when Ms. barkeri was grown on different substrates [118]. Obligately methylotrophic methanogenic bacteria contain the enzyme [83,119] or are able to produce H 2 from formate by formate hydrogen lyase [82].…”

Section: Hydrogen Metabolism In Mixed and Pure Cultures Of Methanogenmentioning

confidence: 99%

Electron transfer reactions in methanogens

Keltjens

Drift

1986

FEMS Microbiology Letters

112

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Methanogenic bacteria comprise a specialized group of obligately anaerobic microorganisms able to reduce a limited number of substrates to CH4. The intermediates involved in this reduction process remain bound to a series of typical C1‐carriers. Reducing equivalents are either obtained from the oxidation of H2 or from oxidation of carbon substrates to CO2. Electron transfer reactions thus constitute the very essence of the process of methanogenesis. In recent years much progress has been made in the elucidation of the special metabolic pathways and the nature of the C1‐carriers involved in methanogenic bacteria. The energy generated at the oxidoreduction reactions, notably at the methylreductase step, is conserved by ATP synthesis. The energy is used for cell carbon synthesis and, in catalytic amounts, for the reductive activation of some methanogenic enzymes. Before the condensing reaction resulting in the formation of acetyl‐CoA takes place, 2 C1‐units are reduced or oxidized depending on the substrate to a carbonyl and a ‐CH3 group. Formation of the latter proceeds via the methanogenic route. Intermediary cell carbon synthesis starting from acetyl‐CoA involves reductive carboxylations and oxidoreductions by the participation of the enzymes of the tricarboxylic acid cycle.

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Levels of coenzyme F420, coenzyme M, hydrogenase, and methylcoenzyme M methylreductase in acetate-grown Methanosarcina

Cited by 38 publications

References 17 publications

Methanogenesis in Marine Sediments

Methanogenesis in Marine Sediments

Analysis of hydrogen metabolism in Methanosarcina barkeri: Regulation of hydrogenase and role of CO-dehydrogenase in H2 production

Electron transfer reactions in methanogens

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