Phylloxin, a novel peptide antibiotic of the dermaseptin family of antimicrobial/opioid peptide precursors
2000
Pierre, Thierry N. | Seon, Aurélia A. | Amiche, Mohamed | Nicolas, Pierre
A novel family of peptide precursors that have very similar Nâterminal preprosequences followed by markedly different Câterminal domains has been identified in the skin of hylid frogs belonging to the genus Phyllomedusinae. Biologically active peptides derived from the variable domains include the dermaseptins, 28–34âresidue peptides that have a broadâspectrum microbicidal activity, and dermorphin and the deltorphins, dâamino acid containing heptapeptides that are very potent agonists for the µâopioid and δâopioid receptors, respectively. This report describes the isolation, synthesis and cloning of phylloxin, a prototypical member of a novel family of antimicrobial peptides derived from the processing of a dermaseptin/dermorphinâlike precursor. The structure of phylloxin (GWMSKIASGIGTFLSGIQQ amide) shows no homology to the dermaseptins, but bears some resemblance to the levitideâprecursor fragment and the xenopsinâprecursor fragment, two antimicrobial peptides isolated from the skin of an evolutionarily distant frog species, Xenopus laevis. Circular dichroism spectra of phylloxin in low polarity medium, which mimics the lipophilicity of the membrane of target microorganisms, indicated 60–70% αâhelical conformation, and predictions of secondary structure suggested that the peptide can be configured as an amphipathic helix spanning residues 1–19. Phylloxin is an addition to the structurally and functionally diverse peptide families encoded by the rapidly evolving Câterminal domains of the dermorphin/dermaseptin group of precursors.
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