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Wood–Ljungdahl pathway

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This is an old revision of this page, as edited by Glaciimonas (talk | contribs) at 18:19, 4 February 2020 (Edited first line to clarify taxonomic placement of acetogens and methanogens. Added line in third paragraph to expand on anaerobic bacterial use of the reverse pathway, with new reference. Edited first line of final paragraph, again to clarify taxonomy of acetogens and methanogens.). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

The reductive acetyl–CoA pathway

The Wood–Ljungdahl pathway is a set of biochemical reactions used by some bacteria and archaea called acetogens and methanogens, respectively. It is also known as the reductive acetyl-coenzyme A (Acetyl-CoA) pathway.[1] This pathway enables these organisms to use hydrogen as an electron donor, and carbon dioxide as an electron acceptor and as a building block for biosynthesis.

In this pathway carbon dioxide is reduced to carbon monoxide and formic acid or directly into a formyl group, the formyl group is reduced to a methyl group and then combined with the carbon monoxide and Coenzyme A to produce acetyl-CoA. Two specific enzymes participate on the carbon monoxide side of the pathway: CO Dehydrogenase and acetyl-CoA synthase. The former catalyzes the reduction of the CO2 and the latter combines the resulting CO with a methyl group to give acetyl-CoA.[1][2]

Some anaerobic bacteria and archaea use the Wood-Ljungdahl pathway in reverse to break down acetate. For example, some methanogens break down acetate to a methyl group and carbon monoxide, and then reduce the methyl group to methane while oxidizing the carbon monoxide to carbon dioxide.[3] Sulfate reducing bacteria, meanwhile, oxidize acetate completely to CO2 and H2 coupled with the reduction of sulfate to sulfide[4]. When operating in the reverse direction, the acetyl-CoA synthase is sometimes called acetyl-CoA decarbonylase.

The pathway occurs in both bacteria (e.g. acetogens) and archaea (e.g. methanogens[5]). Unlike the Reverse Krebs cycle and the Calvin cycle, this process is not cyclic. A recent study of the genomes of a set of bacteria and archaea suggests that the last universal common ancestor (LUCA) of all cells was using the Wood–Ljungdahl pathway in a hydrothermal setting.[6] Phylometabolic reconstructions[7] as well as chemical experiments suggest the pathway may have prebiotic origins.[8]

See also

References

  1. ^ a b Ragsdale Stephen W (2006). "Metals and Their Scaffolds To Promote Difficult Enzymatic Reactions". Chem. Rev. 106 (8): 3317–3337. doi:10.1021/cr0503153. PMID 16895330.
  2. ^ Paul A. Lindahl "Nickel-Carbon Bonds in Acetyl-Coenzyme A Synthases/Carbon Monoxide Dehydrogenases" Met. Ions Life Sci. 2009, volume 6, pp. 133–150. doi:10.1039/9781847559159-00133
  3. ^ Can, Mehmet; Armstrong, Fraser A.; Ragsdale, Stephen W. (2014-04-23). "Structure, Function, and Mechanism of the Nickel Metalloenzymes, CO Dehydrogenase, and Acetyl-CoA Synthase". Chemical Reviews. 114 (8): 4149–4174. doi:10.1021/cr400461p. ISSN 0009-2665. PMC 4002135. PMID 24521136.
  4. ^ Spormann, Alfred M.; Thauer, Rudolf K. (1988). "Anaerobic acetate oxidation to CO2 by Desulfotomaculum acetoxidans". Archives of Microbiology. 150 (4): 374–380. doi:10.1007/BF00408310. ISSN 0302-8933. {{cite journal}}: Cite has empty unknown parameter: |1= (help)
  5. ^ Matschiavelli, N.; Oelgeschlager, E.; Cocchiararo, B.; Finke, J.; Rother, M. (2012). "Function and regulation of isoforms of carbon monoxide dehydrogenase/acetyl-CoA synthase in Methanosarcina acetivorans". Journal of Bacteriology. 194 (19): 5377–87. doi:10.1128/JB.00881-12. PMC 3457241. PMID 22865842.
  6. ^ M. C. Weiss; et al. (2016). "The physiology and habitat of the last universal common ancestor". Nature Microbiology. 1 (16116): 16116. doi:10.1038/nmicrobiol.2016.116. PMID 27562259.
  7. ^ Braakman, Rogier; Smith, Eric (2012-04-19). "The Emergence and Early Evolution of Biological Carbon-Fixation". PLOS Computational Biology. 8 (4): e1002455. Bibcode:2012PLSCB...8E2455B. doi:10.1371/journal.pcbi.1002455. ISSN 1553-7358. PMC 3334880. PMID 22536150.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  8. ^ Varma, Sreejith J.; Muchowska, Kamila B.; Chatelain, Paul; Moran, Joseph (2018-04-23). "Native iron reduces CO2 to intermediates and end-products of the acetyl-CoA pathway". Nature Ecology & Evolution. 2 (6): 1019–1024. doi:10.1038/s41559-018-0542-2. ISSN 2397-334X. PMC 5969571. PMID 29686234.

Other reading

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