Structure And Function Analysis Of Black Widow Spider Egg Toxin Latroeggtoxin-Ⅳ

Black widow spider, taxonomically belonging to Arthropoda,Arachnida, Araneae, Theridiidae, Latrodectus, is one of the most poisonous spiders in the word. It was frequently reported that black widow spider attacked on human both in china and abroad, which attracted a lot of attention. Related researchers launched a series of scientific researches to probe into the spider. The black widow spider contains plenty of toxins, which are distributed in different parts of the body, such as venom gland, legs and abdominal tissues. Even the newborn spiderlings and eggs also contain toxic components. It is of great significance for systematical understanding of the black widow spider toxins to study the toxic components in the materials outside the venom glands and reveal possible relationship between these toxins and those from the venom glands.The female black widow spiders lay eggs from May to August each year. They weave sacs to protect eggs and the sacs are usually yellowish-brown. In this work, in order to study the toxic components in the black widow spider eggs, we prepared the aqueous extract of the black widow spider(L. tredecimguttatus) eggs by solution extraction method. Then the molecular sieve chromatography and reversed-phase high performance liquid chromatography were employed to isolate and purify the proteinous components from aqueous extract. Finally we purified a new active component, named Latroeggtoxin-IV. MALDI –TOF-TOF mass spectrometry indicated that the molecular weight(M +H+) of Latroeggtoxin- IV is 3606.223 Da. The analysis of amino acid composition showed that Latroeggtoxin- IV is a peptide containing glutamic acid/glutamine, proline, arginine, serine, leucine, cysteine, etc.Biological activity detection indicated that intraperitoneal injecting of Latroeggtoxin-IV into mice and cockroaches led to no obvious poisoning symptoms of the experimental animals. However, Latroeggtoxin-IV showed inhibitory activity against all five species of bacterial strains tested, S. aureus,B. subtilis, E. coli, S. typhimurium and P. aeruginosa,with the strongest inhibitory activity against S. aureus. Thus,Latroeggtoxin-IV was shown to be a broad-spectrum antibacterial peptide.Preliminary sequencing suggested that Latroeggtoxin-IV may have an intramolecular cycle structure.Using a combination of multiple biochemical and biological strategies, our present work for the first time purified a new antibacterial peptide from the black widow spider eggs and made preliminary studies on its structure and function, which not only provides new clues for further revealing the toxicity mechanism of black widow spider eggs and expands the understanding of spider toxins, but also supplies new candidates for the development of new antibacterial agents.