title: Interaction of the rattlesnake toxin crotamine with model membranes.
abstract: Crotamine is one of the main constituents of the venom of the South American rattlesnake Crotalus durissus terrificus. A common gene ancestry and structural similarity with the antimicrobial β-defensins (identical disulfide bond pattern and highly positive net charge) suggested potential antimicrobial activities for this snake toxin. Although crotamine demonstrated low activity against both Gram-positive and Gram-negative bacteria, a pronounced antifungal activity was observed against Candida spp., Trichosporon spp., and Cryptococcus neoformans. Crotamine's selective antimicrobial properties, with no observable hemolytic activity, stimulated us to evaluate the potential applications of this polypeptide as an antiyeast or candicidal agent for medical and industrial application. Aiming to understand the mechanism(s) of action underlying crotamine antimicrobial activity and its selectivity for fungi, we present herein studies using membrane model systems (i.e., large unilamellar vesicles, LUVs, and giant unilamellar vesicles, GUVs), with different phospholipid compositions. We show here that crotamine presents a higher lytic activity on negatively charged membranes compared with neutral membranes, with or without cholesterol or ergosterol content. The vesicle burst was not preceded by membrane permeabilization as is generally observed for pore forming peptides. Although such a property of disrupting lipid membranes is very important to combat multiresistant fungi, no inhibitory activity was observed for crotamine against biofilms formed by several Candida spp. strains, except for a limited effect against C. krusei biofilm.
authors.affiliation: Departamento de Farmacologia, Universidade Federal de São Paulo (UNIFESP) , São Paulo 04044-020, Brazil.
authors.forename: Bruno A
authors.initials: BA
authors.lastname: Costa
authors.forename: Leonardo
authors.initials: L
authors.lastname: Sanches
authors.forename: Andreza Barbosa
authors.initials: AB
authors.lastname: Gomide
authors.forename: Fernando
authors.initials: F
authors.lastname: Bizerra
authors.forename: Caroline
authors.initials: C
authors.lastname: Dal Mas
authors.forename: Eduardo B
authors.initials: EB
authors.lastname: Oliveira
authors.forename: Katia Regina
authors.initials: KR
authors.lastname: Perez
authors.forename: Rosangela
authors.initials: R
authors.lastname: Itri
authors.forename: Nancy
authors.initials: N
authors.lastname: Oguiura
authors.forename: Mirian A F
authors.initials: MA
authors.lastname: Hayashi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000935:Antifungal Agents / Q000494:pharmacology; D003435:Crotalid Venoms / Q000737:chemistry* / Q000378:metabolism / Q000633:toxicity; D017839:Crotalus / Q000378:metabolism*; D005658:Fungi / Q000187:drug effects; D006090:Gram-Negative Bacteria / Q000187:drug effects; D006094:Gram-Positive Bacteria / Q000187:drug effects; D008853:Microscopy; D008969:Molecular Sequence Data; D053835:Unilamellar Liposomes / Q000737:chemistry* / Q000378:metabolism
chemical_list: D000935:Antifungal Agents; D003435:Crotalid Venoms; D053835:Unilamellar Liposomes; C010563:crotamine