Streptopeptolin, a Cyanopeptolin-Type Peptide from Streptomyces olivochromogenes

Cyanopeptolin-type peptides are cyclic depsipeptides that commonly have 3-amino-6-hydroxy-2-piperidone (Ahp) unit in the molecules. So far, cyanopeptolin-type peptides have been isolated as protease inhibitors from a wide variety of cyanobacteria. In the course of screening for new peptides, a new peptide streptopeptolin, which had the similar structure to cyanopeptolin, was isolated from the extract of Streptomyces olivochromogenes NBRC 3561. Streptopeptolin is the first cyanopeptolin-type peptide isolated from actinobacteria. The structure of streptopeptolin was determined by the analysis of electrospray ionization mass spectrometry and NMR to be cyclic depsipeptide containing unusual amino acids, Ahp, and N-methyl tyrosine. As a result of protease inhibition test, streptopeptolin showed inhibitory activity against chymotrypsin. The whole genome sequence data of S. olivochromogenes revealed the biosynthetic gene cluster for streptopeptolin, which encoded a nonribosomal peptide synthetase. We proposed a biosynthetic pathway of streptopeptolin based on bioinformatics analysis.