Structure and Biosynthesis of the Ribosomal Lipopeptide Antibiotic Albopeptins

Albopeptins produced by Streptomyces albofaciens JC-82-120 were isolated as effective antibiotics for plant pathogenetic disease in 1986. However, their unusual physicochemical properties hampered the determination of their chemical structures. In this report, we describe our efforts to elucidate their structures. Initially, the structure of an unusual C13-fatty acid with an N-hydroxyguanidyl group was determined using degradation and chemical synthesis. After the linear portion of the octapeptide core was constructed based on the 2D-NMR data, the final assembly of the unusual structure, including the sulfoxide bridge, was achieved through the analysis of detailed NMR data. The proposed structure of albopeptin B was supported by MS/MS data, which also enabled us to determine the structure of 5 albopeptin family members. Bioinformatics analysis of the genomic data of the producer strain further led us to propose that their biosynthetic pathway is similar to the ribosomally derived lanthipeptides possessing a long-chain fatty acid.