title: Crystallization of a membrane pore-forming protein with mosquitocidal activity from Bacillus thuringiensis subspecies kyushuensis.
abstract: CytB, a membrane pore-forming toxin from Bacillus thuringiensis subspecies kyushuensis, is specifically toxic to dipteran insect larvae but broadly cytolytic in vitro. It has been purified in the protoxin form from a recombinant Escherichia coli source and crystals have been obtained which diffract X-rays to at least 2.6 A resolution. The tendency for CytB to aggregate in solution was overcome by including 50 mM of urea or 8 mM of ethanolamine during crystallization. Mutants designed to add or subtract single cysteine residues for the purpose of heavy atom derivative preparation were similarly purified and crystallized. The crystals are hexagonal bipyramids. They belong to space group P6(1)22 (or P6(5)22) with lattice constants a = b = 67.34 A, c = 170.96 A, and contain one molecule of the CytB protoxin (MW 29235) per asymmetric unit and 27% solvent by volume.
authors.affiliation: MRC Laboratory of Molecular Biology, Cambridge, U.K.
authors.forename: J
authors.initials: J
authors.lastname: Li
authors.forename: P A
authors.initials: PA
authors.lastname: Koni
authors.forename: D J
authors.initials: DJ
authors.lastname: Ellar
mesh_terms: D001413:Bacillus thuringiensis / Q000737:chemistry* / Q000235:genetics; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D001427:Bacterial Toxins; D003460:Crystallization; D018360:Crystallography, X-Ray; D004731:Endotoxins / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D006460:Hemolysin Proteins; D016297:Mutagenesis, Site-Directed; D017354:Point Mutation; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004731:Endotoxins; D006460:Hemolysin Proteins; D011994:Recombinant Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis