STRUCTURAL ELUCIDATION OF XR586, A PEPTAIBOL-LIKE ANTIBIOTIC FROM ACREMONIUM-PESICINUM

A novel peptide, XR586, has been isolated from fermentations of Acremo nium persicinum (Xenova culture collection number X21488). The structu re of XR586 has been elucidated by means of NMR spectroscopy, electros pray and fast-atom bombardment MS, derivatization and enzymic digestio n. It has been shown to be helical by CD measurements. XR586 shows man y structural and conformational features in common with peptaibols, pa rticularly the zervamicins. Peptaibol antibiotics are peptides, typica lly of 15-20 residues, containing a large proportion of alpha-aminoiso butyric acid (Aib) residues. These peptides adopt a helical conformati on in solution and display anti-bacterial and toxic properties due to their ability to form pores in membranes. However, while XR586 contain s several Aib residues, it lacks a terminal phenylalaninol and termina tes in the sequence Phe-Gly. The lack of reduction of the penultimate residue at the C-terminus may indicate that this step is normally at t he end of the biosynthetic pathway of peptaibols and occurs with cleav age of Gly. The H-1 chemical shift assignments of XR586 are reported i n Supplementary Publication SUP 50179 (3 pages), which has been deposi ted at the British Library Document Supply Centre, Boston Spa, Wetherb y, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J.(1996) 313, 9 ('Deposition of data') .