La crotalicidina, un péptido del veneno de una serpiente de cascabel, tiene entre otras propiedades una potente acción antimicrobiana. Un fragmento resultante de la disección racional del péptido nativo presenta propiedades mejoradas en cuanto a selectividad y estabilidad. En el trabajo se detalla a nivel molecular el mecanismo por el cual ambos péptidos ejercen su acción bactericida interaccionando con la membrana bacteriana.
Resumen
Crotalicidin (Ctn), a cathelicidin-related peptide from the venom of a South American rattlesnake, possesses potent antimicrobial, antitumor, and antifungal properties. Previously, we have shown that its C-terminal fragment, Ctn(15-34), retains the antimicrobial and antitumor activities but is less toxic to healthy cells and has improved serum stability. Here, we investigated the mechanisms of action of Ctn and Ctn(15-34) against Gram-negative bacteria. Both peptides were bactericidal, killing ∼90% of Escherichia coli and Pseudomonas aeruginosa cells within 90-120 and 5-30 min, respectively. Studies of ζ potential at the bacterial cell membrane suggested that both peptides accumulate at and neutralize negative charges on the bacterial surface. Flow cytometry experiments confirmed that both peptides permeabilize the bacterial cell membrane but suggested slightly different mechanisms of action. Ctn(15-34) permeabilized the membrane immediately upon addition to the cells, whereas Ctn had a lag phase before inducing membrane damage and exhibited more complex cell-killing activity, probably because of two different modes of membrane permeabilization. Using surface plasmon resonance and leakage assays with model vesicles, we confirmed that Ctn(15-34) binds to and disrupts lipid membranes and also observed that Ctn(15-34) has a preference for vesicles that mimic bacterial or tumor cell membranes. Atomic force microscopy visualized the effect of these peptides on bacterial cells, and confocal microscopy confirmed their localization on the bacterial surface. Our studies shed light onto the antimicrobial mechanisms of Ctn and Ctn(15-34), suggesting Ctn(15-34) as a promising lead for development as an antibacterial/antitumor agent.
Sobre el grupo investigador
El grupo de Investigación en Proteómica y Química de Proteínas dirigido por David Andreu en la Universidad Pompeu Fabra, cuenta con una amplia trayectoria en el diseño, optimización y síntesis de péptidos terapéuticos, específicamente en el campo del desarrollo de vacunas peptídicas y péptidos antimicrobianos contra bacterias multirresistentes, protozoos y hongos.
Referencia del artículo
Pérez-Peinado C, Dias SA, Domingues MM, Benfield AH, Freire JM, Rádis-Baptista G, Gaspar D, Castanho MARB, Craik DJ, Henriques ST, Veiga AS, Andreu D. Mechanisms of bacterial membrane permeabilization by crotalicidin (Ctn) and its fragment Ctn(15-34), antimicrobial peptides from rattlesnake venom. J Biol Chem. 2018 Feb 2;293(5):1536-1549.
https://doi.org/10.1074/jbc.RA117.000125