title: Characterization of Cyt2Bc toxin from Bacillus thuringiensis subsp. medellin.
abstract: We cloned and sequenced a new cytolysin gene from Bacillus thuringiensis subsp. medellin. Three IS240-like insertion sequence elements and the previously cloned cyt1Ab and p21 genes were found in the vicinity of the cytolysin gene. The cytolysin gene encodes a protein 29.7 kDa in size that is 91.5% identical to Cyt2Ba from Bacillus thuringiensis subsp. israelensis and has been designated Cyt2Bc. Inclusions containing Cyt2Bc were purified from the crystal-negative strain SPL407 of B. thuringiensis. Cyt2Bc reacted weakly with antibodies directed against Cyt2Ba and was not recognized by an antiserum directed against the reference cytolysin Cyt1Aa. Cyt2Bc was hemolytic only upon activation with trypsin and had only one-third to one-fifth of the activity of Cyt2Ba, depending on the activation time. Cyt2Bc was also mosquitocidal against Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus, including strains resistant to the Bacillus sphaericus binary toxin. Its toxicity was half of that of Cyt2Ba on all mosquito species except resistant C. quinquefasciatus.
authors.affiliation: Laboratoire des Bactéries et Champignons Entomopathogènes, Institut Pasteur, 25 rue du Dr. Roux, 75724 Paris Cedex 15, France.
authors.forename: Victor
authors.initials: V
authors.lastname: Juárez-Pérez
authors.forename: Alejandra
authors.initials: A
authors.lastname: Guerchicoff
authors.forename: Clara
authors.initials: C
authors.lastname: Rubinstein
authors.forename: Armelle
authors.initials: A
authors.lastname: Delécluse
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis / Q000235:genetics / Q000378:metabolism*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism / Q000633:toxicity*; D001427:Bacterial Toxins; D003001:Cloning, Molecular; D009033:Culicidae / Q000187:drug effects*; D004731:Endotoxins / Q000235:genetics* / Q000378:metabolism / Q000633:toxicity*; D006460:Hemolysin Proteins; D006461:Hemolysis; D008969:Molecular Sequence Data; D015183:Restriction Mapping; D017422:Sequence Analysis, DNA
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis