Cyclic lipoundecapeptide amphisin from Pseudomonas sp strain DSS73

The crystal structure of the lipoundecapeptide amphisin, presented here as the tetrahydrate, C66H114N12O20. 4H(2)O, originating from non-ribosomal bio synthesis by Pseudomonas sp. strain DSS73, has been solved to a resolution of 0.65 Angstrom. The primary structure of amphisin is beta -hydroxydecanoy ld-Leu-D-Asp-D-allo-Thr-D-Leu-D-Leu-D-Ser-L-Leu-D-Gln-L- Leu-l-Ile-l-Asp (L eu is leucine, Asp is aspartic acid, Thr is threonine, Ser is serine, Gln i s glutamine and Ile is isoleucine). The peptide is a lactone, linking Thr4 O-gamma to the C-terminal. The stereochemistry of the beta -hydroxy acid is R. The peptide is a close analogue of the cyclic lipopeptides tensin and p holipeptin produced by Pseudomonas fluorescens. The structure of amphisin i s mainly helical (3(10)-helix), with the cyclic peptide wrapping around a h ydrogen-bonded water molecule. This lipopeptide is amphiphilic and has bios urfactant and antifungal properties.