YddG from Escherichia coli promotes export of aromatic amino acids

FEMS Microbiol Lett. 2007 Oct;275(2):312-8. doi: 10.1111/j.1574-6968.2007.00894.x. Epub 2007 Sep 3.


The inner membrane protein YddG of Escherichia coli is a homologue of the known amino acid exporters RhtA and YdeD. It was found that the yddG gene overexpression conferred resistance upon E. coli cells to the inhibiting concentrations of l-phenylalanine and aromatic amino acid analogues, dl-p-fluorophenylalanine, dl-o-fluorophenylalanine and dl-5-fluorotryptophan. In addition, yddG overexpression enhanced the production of l-phenylalanine, l-tyrosine or l-tryptophan by the respective E. coli-producing strains. On the other hand, the inactivation of yddG decreased the aromatic amino acid accumulation by these strains. The cells of the E. colil-phenylalanine-producing strain containing overexpressed yddG accumulated less l-phenylalanine inside and exported the amino acid at a higher rate than the cells of the isogenic strain containing wild-type yddG. Taken together, these results indicate that YddG functions as an aromatic amino acid exporter.

MeSH terms

  • Amino Acids, Aromatic / metabolism*
  • Culture Media
  • Escherichia coli / genetics
  • Escherichia coli / growth & development
  • Escherichia coli / metabolism*
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism*
  • Gene Expression Regulation, Bacterial*
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Protein Transport


  • Amino Acids, Aromatic
  • Culture Media
  • Escherichia coli Proteins
  • Membrane Proteins
  • RhtA protein, E coli