A polyketide synthase in glycopeptide biosynthesis: the biosynthesis of the non-proteinogenic amino acid (S)-3,5-dihydroxyphenylglycine

J Biol Chem. 2001 Oct 19;276(42):38370-7. doi: 10.1074/jbc.M106580200. Epub 2001 Aug 8.


Balhimycin, a vancomycin-type antibiotic from Amycolatopsis mediterranei, contains the unusual amino acid (S)-3,5-dihydroxyphenylglycine (Dpg), with an acetate-derived carbon backbone. After sequence analysis of the biosynthetic gene cluster, one gene, dpgA, for a predicted polyketide synthase (PKS) was identified, sharing 20-30% identity with plant chalcone synthases. Inactivation of dpgA resulted in loss of balhimycin production, and restoration was achieved by supplementation with 3,5-dihydroxyphenylacetic acid, which is both a possible product of a PKS reaction and a likely precursor of Dpg. Enzyme assays with the protein expressed in Streptomyces lividans showed that this PKS uses only malonyl-CoA as substrate to synthesize 3,5-dihydroxyphenylacetic acid. The PKS gene is organized in an operon-like structure with three downstream genes that are similar to enoyl-CoA-hydratase genes and a dehydrogenase gene. The heterologous co-expression of all four genes led to accumulation of 3,5-dihydroxyphenylglyoxylic acid. Therefore, we now propose a reaction sequence. The final step in the pathway to Dpg is a transamination. A predicted transaminase gene was inactivated, resulting in abolished antibiotic production and accumulation of 3,5-dihydroxyphenylglyoxylic acid. Interestingly, restoration was only possible by simultaneous supplementation with (S)-3,5-dihydroxyphenylglycine and (S)-4-hydroxyphenylglycine, indicating that the transaminase is essential for the formation of both amino acids.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acids / biosynthesis
  • Bacterial Proteins*
  • Chromatography, High Pressure Liquid
  • Coenzyme A Ligases / biosynthesis
  • Coenzyme A Ligases / chemistry*
  • Coenzyme A Ligases / genetics*
  • Excitatory Amino Acid Antagonists / chemistry*
  • Gene Deletion
  • Glycine / analogs & derivatives
  • Glycine / biosynthesis*
  • Glycine / chemistry*
  • Glycopeptides / biosynthesis
  • Models, Chemical
  • Models, Genetic
  • Molecular Sequence Data
  • Multienzyme Complexes / chemistry*
  • Multienzyme Complexes / metabolism*
  • Mutagenesis, Site-Directed
  • Plasmids / metabolism
  • Resorcinols / chemistry*
  • Sequence Analysis, DNA
  • Streptomyces / enzymology
  • Vancomycin / analogs & derivatives*
  • Vancomycin / biosynthesis


  • Amino Acids
  • Bacterial Proteins
  • DpgA protein, Amycolatopsis mediterranei
  • Excitatory Amino Acid Antagonists
  • Glycopeptides
  • Multienzyme Complexes
  • Resorcinols
  • balhimycin
  • 3,5-dihydroxyphenylglycine
  • Vancomycin
  • Coenzyme A Ligases
  • Glycine

Associated data

  • GENBANK/Y16952