Biosynthetic Precursors of Etamycin, a Peptidolactone Antibiotic from Streptomyces griseoviridus

Abstract

Radiotracer studies of the incorporation of labeled amino acids have established the biosynthetic precursors of etamycin. L-[U-¹⁴C]threonine and L-[U-¹⁴C]alanine were incorporated into the corresponding moieties in the antibiotic. Sarcosine was derived from [1-¹⁴C]glycine but [1-¹⁴C]sarcosine was also an efficient precursor. L-[U-¹⁴C]leucine was incorporated equally well into the D-leucine and N-β-dimethyl-L-leucine moieties. L-α-Phenylsarcosine originated from phenylalanine, the carboxyl-, α-, and phenyl-carbons being derived from ¹⁴C-labeled α-, β-, and phenyl-carbons of the precursor. A small incorporation of L-[carboxy-¹⁴C]phenylalanine into the carboxyl-carbon of phenylsarcosine was also observed. L-[Me-¹⁴C]methionine labeled the methyl groups of sarcosine, phenylsarcosine, and the two substituent methyl groups of dimethylleucine. L-[U-¹⁴C]proline and 4-hydroxy-L-[G-³H]proline were both incorporated efficiently into the allo-4-hydroxy-D-proline component of etamycin. 3-Hydroxypicolinic acid was labeled specifically by L-[U-¹⁴C]lysine, and also by exogenousiy supplied 3-hydroxy[G-³H]picolinic acid.