title: Lycotoxins, antimicrobial peptides from venom of the wolf spider Lycosa carolinensis.
abstract: Two peptide toxins with antimicrobial activity, lycotoxins I and II, were identified from venom of the wolf spider Lycosa carolinensis (Araneae: Lycosidae) by virtue of their abilities to reduce ion and voltage gradients across membranes. Both peptides were purified to homogeneity by reversed-phase liquid chromatography and determined to have the following primary structures by Edman microsequencing: IWLTALKFLGKHAAKHLAKQQLSKL-NH2 for lycotoxin I and KIKWFKTMKSIAKFIAKEQMKKHLGGE-OH for lycotoxin II. The predicted secondary structures of the lycotoxins display amphipathic alpha-helix character typical of antimicrobial pore-forming peptides. Antimicrobial assays showed that both lycotoxins potently inhibit the growth of bacteria (Escherichia coli) and yeast (Candida glabrata) at micromolar concentrations. To verify its hypothesized pore-forming activity, lycotoxin I was synthesized and shown to promote efflux of Ca2+ from synaptosomes, to cause hemolysis of erythrocytes, and to dissipate voltage gradients across muscle membrane. The lycotoxins may play a dual role in spider-prey interaction, functioning both in the prey capture strategy as well as to protect the spider from potentially infectious organisms arising from prey ingestion. Spider venoms may represent a potentially new source of novel antimicrobial agents with important medical implications.
authors.affiliation: Environmental Toxicology Graduate Program, University of California, Riverside 92521, USA.
authors.forename: L
authors.initials: L
authors.lastname: Yan
authors.forename: M E
authors.initials: ME
authors.lastname: Adams
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides; D002118:Calcium / Q000378:metabolism; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D051381:Rats; D016415:Sequence Alignment; D013111:Spider Venoms / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D013112:Spiders; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D010455:Peptides; D013111:Spider Venoms; C110534:lycotoxin I; C110535:lycotoxin II; C066945:magainin B; D002118:Calcium