The biosynthesis of the antibiotic pyrrolnitrin by pseudomonas aureofaciens

Abstract

Feeding experiments with tryptophan samples labeled specifically with radioactive and stable isotopes have shown that Pseudomonas aureofaciens converts this amino acid into pyrrolnitrin in such a way that the indole nitrogen gives rise to the nitro group, the amino group becomes the pyrrole nitrogen, C-3 of the precursor side chain becomes C-3 of the antibiotic, and H-2 of the indole ring and H-a of the side chain give rise to H-5 and H-2 of pyrrolnitrin, respectively. Only the L-isomer of tryptophan is incorporated with retention of the α-hydrogen and the amino nitrogen. From the D-isomer the labels from these two positions are lost. The obvious conclusion that L-tryptophan is the more immediate precursor is, however, contradicted by the better incorporation of D- THAN L-tryptophan into the antibiotic. Several potential pathway intermediates were evaluated for incorporation and 4-(o-aminophenyl)-pyrrole was found to be a good precursor. The results are discussed in terms of a plausible pathway for pyrrolnitrin biosynthesis. © 1981, JAPAN ANTIBIOTICS RESEARCH ASSOCIATION. All rights reserved.