Ocellatin-PT antimicrobial peptides: high-resolution microscopy studies in antileishmania models and interactions with mimetic membrane systems

Although the mechanism of action of antimicrobial peptides (AMPs) is not clear, they can interact electrostatically with the cell membranes of microorganisms. New ocellatin-PT peptides were recently isolated from the skin secretion of Leptodactylus pustulatus. The secondary structure of these AMPs and their effect on Leishmania infantum cells, and on different lipid surface models was characterized in this work. The results showed that all ocellatin-PT peptides have an -helix structure and five of them (PT3, PT4, PT6 to PT8) have leishmanicidal activity; PT1 and PT2 affected the cellular morphology of the parasites and showed greater affinity for leishmania and bacteria-mimicking lipid membranes than for those of mammals. The results show selectivity of ocellatin-PTs to the membranes of microorganisms and the applicability of biophysical methods to clarify the interaction of AMPs with cell membranes. ; This work was partially supported by grants from INCT Nanobiotecnologia and PVE Project (MCT/CNPq), the Consejo Nacional de Investigaciones Cientificas y Técnicas (CONICET), and the Agencia Nacional de Promocion Científica y Tecnologica (ANPCyT). M.M.M.is a researcher at CONICET. This work has also been supported through project UID/MULTI/04378/2013-POCI/01/0145/FEDER/007728 with financial support from FCT/MEC through national funds and co-financed by FEDER, under the Partnership Agreement PT2020. Scanning electron microscopy was carried out at Centro de Materiais da Universidade do Porto, CEMUP. Peter Eaton is supported by a Ciência sem Fronteiras grant via CNPq, and his lab work is supported by financial support from FCT/MEC through national funds and co-financed by FEDER, under the partnership agreement PT2020. Alexandra Pl acido and Ana Georgina Gomes-Alves are grateful to FCT for their grants SFRH/BD/97995/2013 and SFRH/BD/93766/2013, financed by POPH–QREN–Tipologia 4.1–Formação Avançada, subsidized by Fundo Social Europeu and Ministério da Ciência, Tecnologia e Ensino Superior. Nuno Vale thanks Programa Operacional ...