A novel paradigm of fatty acid beta-oxidation exemplified by the thioesterase-dependent partial degradation of conjugated linoleic acid that fully supports growth of Escherichia coli

Biochemistry. 2008 Sep 9;47(36):9618-26. doi: 10.1021/bi801074e. Epub 2008 Aug 15.


An alternative pathway of beta-oxidation for unsaturated fatty acids was studied in Escherichia coli. 9- cis,11- trans-Octadecadienoic acid (conjugated linoleic acid), a potential substrate of this pathway, was shown to support growth of E. coli in the absence of any other carbon source. The identification of 3,5-dodecadienoic acid in the growth medium revealed the partial beta-oxidation of conjugated linoleic acid to 3,5-dodecadienoyl-CoA, which was hydrolyzed to 3,5-dodecadienoic acid and released from cells. The involvement of acyl-CoA thioesterases in this process was evaluated by determining the substrate specificity of thioesterase II and comparing it with that of a novel thioesterase (thioesterase III) and by assessing mutant strains devoid of one or both of these thioesterases for growth on conjugated linoleic acid. Both thioesterases were highly active with 3,5-dodecadienoyl-CoA as substrate. A deficiency of either thioesterase decreased the growth rate of cells on conjugated linoleic acid but not on palmitic acid. The absence of both thioesterases reduced the cellular growth in a cumulative manner but did not abolish it. It is concluded that thioesterases II and III and at least one other thioesterase function in the partial degradation of conjugated linoleic acid via the thioesterase-dependent pathway of beta-oxidation, which provides all energy and carbon precursors required for the growth of E. coli.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Escherichia coli / enzymology*
  • Escherichia coli / genetics
  • Escherichia coli / growth & development*
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism*
  • Fatty Acid Synthases / genetics
  • Fatty Acid Synthases / metabolism*
  • Linoleic Acids, Conjugated / genetics
  • Linoleic Acids, Conjugated / metabolism*
  • Linoleic Acids, Conjugated / pharmacology*
  • Lipid Metabolism / drug effects
  • Lipid Metabolism / physiology
  • Mutation
  • Oxidation-Reduction / drug effects
  • Palmitic Acid / metabolism
  • Palmitic Acid / pharmacology
  • Thiolester Hydrolases / genetics
  • Thiolester Hydrolases / metabolism*


  • Escherichia coli Proteins
  • Linoleic Acids, Conjugated
  • 9,11-linoleic acid
  • Palmitic Acid
  • Fatty Acid Synthases
  • Thiolester Hydrolases
  • thioesterase II