Crabtree effect

Named after the English biochemist Herbert Grace Crabtree, the Crabtree effect describes the phenomenon whereby the yeast, Saccharomyces cerevisiae, produces ethanol (alcohol) in aerobic conditions and high external glucose concentrations rather than producing biomass via the tricarboxylic acid (TCA) cycle, the usual process occurring aerobically in most yeasts e.g. Kluyveromyces spp[1]. This phenomenon is observed in most species of the Saccharomyces, Schizosaccharomyces, Debaryomyces, Brettanomyces, Torulopsis, Nematospora, and Nadsonia genera.[2] Increasing concentrations of glucose accelerates glycolysis (the breakdown of glucose) which results in the production of appreciable amounts of ATP through substrate-level phosphorylation. This reduces the need of oxidative phosphorylation done by the TCA cycle via the electron transport chain and therefore decreases oxygen consumption. The phenomenon is believed to have evolved as a competition mechanism (due to the antiseptic nature of ethanol) around the time when the first fruits on Earth fell from the trees.[1] The crabtree effect works by repressing respiration by the fermentation pathway, dependent on the substrate.[3] The occurrence of alcoholic fermentation is not primarily due to a limited respiratory capacity.[4]

References

  1. 1 2 Thomson JM, Gaucher EA, Burgan MF, De Kee DW, Li T, Aris JP, Benner SA (2005). "Resurrecting ancestral alcohol dehydrogenases from yeast". Nat. Genet. 37 (6): 630–635. doi:10.1038/ng1553. PMC 3618678. PMID 15864308.
  2. ↑ De Deken, R. H. (1966). "The Crabtree Effect: A Regulatory System in Yeast". J. Gen. Microbiol. 44: 149–56. doi:10.1099/00221287-44-2-149. PMID 5969497.
  3. ↑ De Deken, R. H. (1 August 1966). "The Crabtree Effect and its Relation to the Petite Mutation". Journal of General Microbiology. 44 (2): 157–165. doi:10.1099/00221287-44-2-157.
  4. ↑ Postma, E; Verduyn, C; Scheffers, WA; Van Dijken, JP (February 1989). "Enzymic analysis of the crabtree effect in glucose-limited chemostat cultures of Saccharomyces cerevisiae". Applied and Environmental Microbiology. 55 (2): 468–77. PMID 2566299.

Further reading

  • Crabtree HG (1928). "The carbohydrate metabolism of certain pathological overgrowths". Biochem. J. 22 (5): 1289–98. PMC 1252256. PMID 16744142.


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