Peptidomic Analysis of Skin Secretions of the Caribbean Frogs Leptodactylus insularum and Leptodactylus nesiotus (Leptodactylidae) Identifies an Ocellatin with Broad Spectrum Antimicrobial Activity

Gervonne Barran (1) , Jolanta Kolodziejek (2) , Laurent Coquet (3, 4) , Jérôme Leprince (5, 6) , Thierry Jouenne (3) , Norbert Nowotny (7, 2) , J. Michael Conlon (8) , Milena Mechkarska (1)

1 The University of the West Indies
2 Vetmeduni - University of Veterinary Medicine [Vienna]
3 PBS - Polymères Biopolymères Surfaces
4 Plate-forme de Protéomique PISSARO
5 DC2N - Différenciation et communication neuronale et neuroendocrine
6 PRIMACEN - Plate-Forme de Recherche en Imagerie Cellulaire de Haute-Normandie
7 MBRU - Mohammed Bin Rashid University of Medicine and Health Sciences
8 University of Ulster

Ocellatins are peptides produced in the skins of frogs belonging to the genus Leptodactylus that generally display weak antimicrobial activity against Gram-negative bacteria only. Peptidomic analysis of norepinephrine-stimulated skin secretions from Leptodactylus insularum Barbour 1906 and Leptodactylus nesiotus Heyer 1994, collected in the Icacos Peninsula, Trinidad, led to the purification and structural characterization of five ocellatin-related peptides from L. insularum (ocellatin-1I together with its (1-16) fragment, ocellatin-2I and its (1-16) fragment, and ocellatin-3I) and four ocellatins from L. nesiotus (ocellatin-1N,-2N,-3N, and-4N). While ocellatins-1I,-2I, and-1N showed a typically low antimicrobial potency against Gram-negative bacteria, ocellatin-3N (GIFDVLKNLAKGVITSLAS.NH 2) was active against an antibiotic-resistant strain of Klebsiella pneumoniae and reference strains of Escherichia coli, K. pneumoniae, Pseudomonas aeruginosa, and Salmonella typhimurium (minimum inhibitory concentrations (MICs) in the range 31.25-62.5 µM), and was the only peptide active against Gram-positive Staphylococcus aureus (MIC = 31.25 µM) and Enterococcus faecium (MIC = 62.5 µM). The therapeutic potential of ocellatin-3N is limited by its moderate hemolytic activity (LC 50 = 98 µM) against mouse erythrocytes. The peptide represents a template for the design of long-acting, non-toxic, and broad-spectrum antimicrobial agents for targeting multidrug-resistant pathogens.

Mots clés: antibiotic resistance; antimicrobial peptides; frog skin secretions; hemolysis; Leptodactylus; norepinephrine stimulation; ocellatins; peptidomic analysis; phylogenetics; Trinidad

Domaines: Sciences du Vivant [q-bio]

Gervonne Barran, Jolanta Kolodziejek, Laurent Coquet, Jérôme Leprince, Thierry Jouenne, et al.. Peptidomic Analysis of Skin Secretions of the Caribbean Frogs Leptodactylus insularum and Leptodactylus nesiotus (Leptodactylidae) Identifies an Ocellatin with Broad Spectrum Antimicrobial Activity. Antibiotics, 2020, 9 (10), pp.718. ⟨10.3390/antibiotics9100718⟩. ⟨hal-03053760⟩