Biosynthesis of the antibiotic obafluorin from D-[U-13C]glucose and p-aminophenylalanine in Pseudomonas fluorescens

Abstract

The separate units which are used to construct the antibiotic obafluorin 1 in Pseudomonas fluorescens are defined by the results of D-[U-¹³C]glucose incorporation. A key intermediate in the biosynthesis of 1 is established to be L-p-aminophenylalanine 8; L-phenylalanine and L-p-nitrophenylalanine are very poor precursors. Results similar to those for obafluorin are obtained for p-nitrophenylacetic acid 20 which along with the derivative 4 and 2-(4-nitrophenyl)ethanol 21 are identified as new metabolites of P. fluorescens. Deuteriated samples of 20, 22 and 23 are not precursors for obafluorin 1. [2,3-³H₃]-p-Aminophenylalanine 18 is incorporated into 1 with complete loss of deuterium from C-2 but retention of the deuterium present in both diastereotopic positions on C-3.