Role of betaine:CoA ligase (CaiC) in the activation of betaines and the transfer of coenzyme A in Escherichia coli

J Appl Microbiol. 2008 Jul;105(1):42-50. doi: 10.1111/j.1365-2672.2008.03740.x. Epub 2008 Feb 6.


Aims: Characterization of the role of CaiC in the biotransformation of trimethylammonium compounds into l(-)-carnitine in Escherichia coli.

Methods and results: The caiC gene was cloned and overexpressed in E. coli and its effect on the production of l(-)-carnitine was analysed. Betaine:CoA ligase and CoA transferase activities were analysed in cell free extracts and products were studied by electrospray mass spectrometry (ESI-MS). Substrate specificity of the caiC gene product was high, reflecting the high specialization of the carnitine pathway. Although CoA-transferase activity was also detected in vitro, the main in vivo role of CaiC was found to be the synthesis of betainyl-CoAs. Overexpression of CaiC allowed the biotransformation of crotonobetaine to l(-)-carnitine to be enhanced nearly 20-fold, the yield reaching up to 30% (with growing cells). Higher yields were obtained using resting cells (up to 60%), even when d(+)-carnitine was used as substrate.

Conclusions: The expression of CaiC is a control step in the biotransformation of trimethylammonium compounds in E. coli.

Significance and impact of the study: A bacterial betaine:CoA ligase has been characterized for the first time, underlining its important role for the production of l-carnitine with Escherichia coli.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Betaine / metabolism*
  • Bioreactors
  • Carnitine / biosynthesis
  • Chromatography, High Pressure Liquid
  • Cloning, Molecular
  • Coenzyme A / metabolism*
  • Coenzyme A Ligases / analysis
  • Coenzyme A Ligases / genetics
  • Coenzyme A Ligases / metabolism*
  • Escherichia coli / enzymology*
  • Escherichia coli / genetics
  • Escherichia coli Proteins / analysis
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism*
  • Gene Expression
  • Genes, Bacterial
  • Genetic Vectors
  • Industrial Microbiology*
  • Industrial Waste*
  • Polymerase Chain Reaction / methods
  • Spectrometry, Mass, Electrospray Ionization
  • Substrate Specificity
  • Trimethyl Ammonium Compounds / metabolism


  • Escherichia coli Proteins
  • Industrial Waste
  • Trimethyl Ammonium Compounds
  • Betaine
  • Coenzyme A Ligases
  • caiC protein, E coli
  • Carnitine
  • Coenzyme A