Thaulin-1: The first antimicrobial peptide isolated from the skin of a Patagonian frog Pleurodema thaul (Anura: Leptodactylidae: Leiuperinae) with activity against Escherichia coli

Abstract

Patagonia's biodiversity has been explored from many points of view, however, skin secretions of native amphibians have not been evaluated for antimicrobial peptide research until now. In this sense, Pleurodema thaul is the first amphibian specie to be studied from this large region of South America. Analysis of cDNA-encoding peptide in skin samples allowed identification of four new antimicrobial peptides. The predicted mature peptides were synthesized and all of them showed weak or null antimicrobial activity against Klebsiella pneumoniae, Staphylococcus aureus and Escherichia coli with the exception of thaulin-1, a cationic 26-residue linear, amphipathic, Gly- and Leu-rich peptide with moderate antimicrobial activity against E. coli (MIC of 24.7 M). AFM and SPR studies suggested a preferential interaction between these peptides and bacterial membranes. Cytotoxicity assays showed that thaulin peptides had minimal effects at MIC concentrations towards human and animal cells. These are the first peptides described for amphibians of the Pleurodema genus. These findings highlight the potential of the Patagonian region's unexplored biodiversity as a source for new molecule discovery.This work was partially supported by grants from the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (PIP N° 11220120100050CO), and the Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT) (PICT N° 1199). M.M.M., L.O.P., S.A.C. and N.G.B. are researchers at CONICET. Work in AMT laboratory was supported by Project “NORTE-07-0124-FEDER-000002-Host-Pathogen Interactions” cofunded by Programa Operacional Regional do Norte under QREN, through FEDER (NORTE-07-0124-FEDER-000002-Host-Pathogen Interactions) and FCT. (SFRH/BD/97995/2013, SFRH/BD/93766/2013 and UID/MULTI/04378/2013) A.P. and A.G.G.A. are gratefully to FCT by their grants SFRH/BD/97995/2013 and SFRH/BD/93766/2013 respectively, financed by POPH–QREN–Tipologia 4.1–Formação Avançada, subsidized by Fundo Social Europeu and Ministério da Ciência, Tecnologia e Ensino Superior. The authors thank N.L. Olivera for logistic support and helpful discussions regarding the article. P.E. thanks CNPq for PVE grant no. 400398/2014-1, and is supported by FCTvia the project UID/MULTI/04378/2013