Production of N-Coronafacoyl-L-Amino Acid Analogues of Coronatine by Pseudomonas syringae pv. atropurpurea in Liquid Cultures Supplemented with L-Amino Acids

Summary: Neutral L-amino acids were added to liquid cultures of Pseudomonas syringae pv. atropurpurea that were entering the exponential phase of growth. For each amino acid addition experiment the production of the usual coronafacoyl compounds, coronatine and N-coronafacoyl-L-valine, was diminished and a new product was detected. This was isolated and purified, and established by mass spectrometry and GC analysis of the amino acid released by acid hydrolysis to be the N-coronafacoyl amide of each L-amino acid added to the culture. Coupling was established to occur between coronafacic acid and the L-amino acids alanine, α-aminobutyric acid, norvaline, isoleucine, alloisoleucine, leucine and norleucine. These results suggest that an intracellular enzyme system is operating which lacks an overall rigid specificity in the coupling (amide bond formation) between coronafacic acid and aliphatic neutral amino acids.