XR586 is a peptaibol-like antibiotic isolated from fermentations of Acremonium persicinum. XR586 contains several alpha-aminoisobutyric acid (Aib) residues, lacks a terminal phenylalaninol and terminates in the sequence Phe-Gly[1].
The mechanism of the anti-bacterial activity and toxicity: XR586 shows many structural and conformational features in common with peptaibols, particularly the zervamicins. Peptaibol antibiotics are peptides, typically of 15-20 residues, containing a large proportion of alpha-aminoisobutyric acid (Aib) residues. These peptides adopt a helical conformation in solution and display anti-bacterial and toxic properties due to their ability to form pores in membranes[1].
[1]. G J Sharman, et al. Structural elucidation of XR586, a peptaibol-like antibiotic from Acremonium persicinum. Biochem J. 1996 Dec 15; 320(Pt 3): 723-728.