Synthesis, Membrane Permeability and Effects in Bacteria of the Antimicrobial Peptide LyeTx-I from Venom of the Spider Lycosa erythrognatha (Lycosidae)
Santos, D.M.1, 2; Álvares, E.S.S.7; Diniz, C.G.4; Farias L.M.4; Carvalho, M.A.R.4; Frédéric J. G. Frézard, F.J.G.5; Bemquerer, M.P.2 ,3; De Maria, M.6; Pimenta, A.M.C.1, 2; De Lima, M.1, 2.
1Lab.Venenos e Toxinas Animais; 2Núcleo de Biomoléculas; 3Lab. Enzimologia e Físico-Química de Proteínas - Depto. Bioquímica e Imunologia, 4Lab. de Microbiologia Oral e Anaeróbios – Depto. De Microbiologia; 5Lab. de Biofísica Molecular - Depto. Fisiologia e Biofísica; 6Lab de Aracnobiologia – Depto. de Zoologia – ICB – Universidade Federal de Minas Gerais; 7Lab. de Artrópodes - Instituto Butantan
Introduction and objective: The dramatic increase on frequency of opportunistic bacterial infections has prompted the search into arsenal diversification of antimicrobial agents. Antimicrobial peptides constitute a promising family to future antibiotics with new modes of action. In this work, we aimed to initiate the biological characterization of the synthetic peptide LyeTx-I, a cationic antimicrobial peptide from venom of Lycosa erythrognatha. Methods and results: LyeTx-I was synthesized using the Fmoc method followed by purification by reverse-phase chromatography in HPLC and analysis in mass spectrometer (ESI-Q-TOF). Predicted secondary structures of this sequence show amphipathic a-helices. Antimicrobial assays of LyeTx-I demonstrate activities at nanomolar concentration, inhibiting the growth of bacteria such as Escherichia coli and Staphylococcus aureus. The effect of peptide in membranes was also investigated using liposomes constituted of phosphatidylcholine, cholesterol and ergosterol. The lytic activity was measured by release of calcein from liposomes. The detected minimal activity was at picomolar range. The dose dependency of the membrane permeability caused by LyeTx-I was found to be sigmoidal, suggesting that LyeTx-I oligomerization leads to the membrane permeability. Conclusion: These results show that LyeTx-I may be a good model for the development of new antibiotics against gram-positive and gram-negative bacteria.
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