A Comparison of the Antimicrobial Skin Peptides of the New Guinea Tree Frog (Litoria genimaculata) and the Fringed Tree Frog (Litoria eucnemis)

Abstract

The Fringed Tree Frog (Litoria eucnemis) is closely related to the Tree Frog Litoria genimaculata. Both species are found in northern Australia and New Guinea. We have reported that the major antibiotic peptide of L. genimaculata is maculatin 1.1 which has the sequence GLFGVLAKVAAHVVPAIEHF-NH₂, and that this basic peptide is different from the hinged caerin 1 peptides (e.g. caerin 1.1, from Litoria splendida and other green tree frogs, which has the sequence GLLSVLGSVAKHVLPHVVPVIAEHL-NH₂), in that it lacks four residues of the central hinge region of a caerin 1. Litoria eucnemis has three major host defence peptides, two of these are maculatins (e.g. maculatin 1.3; GLLGLLGSVVSHVVPAIVGHF-NH₂) which are related in sequence to that of maculatin 1. The other antibiotic peptide is caerin 1.11 (GLLGAMFKVASKVLPHVVPAITEHF-NH₂) a peptide related to the caerin 1 peptides of the green tree frogs of Australia. L. eucnemis is the only species of the Litoria genus (that we have studied) which contains both maculatin and caerin peptides in its skin secretion. The three antibiotic peptides of Litoria eucnemis are significantly less active than maculatin 1.1 and other caerins 1 isolated from anurans of the genus Litoria so far studied.