title: [Thermodynamic analysis of domain organization of Bacillus thuringiensis toxins].
abstract: The structure of delta-endotoxins CryIA(c) and CryIIIA from Bacillus thuringiensis was studied by differential scanning microcalorimerty. The analysis of molecular melting showed that the N- and C-terminal halves of the CryIA(c) protoxin from B. thuringiensis subspecies kurstaki HD-73 are thermodynamically independent subunits, with the C-terminal fragment being denatured at a much lower temperature than the N-terminal fragment. The tertiary structure of the N-terminal fragment undergoes no changes during the protoxin-toxin transition. The melting of the native structure of CryIA(c) at pH 9.7-11.0 suggests that it consists of two domains. In CryIIIA from B. thuringiensis subspecies tenebrionis, the transition from the native to denatured state under alkaline conditions (pH 9.7-11.0) proceeds by the "two-state" principle; i.e., the protein melts as one cooperative domain. The melting of the CryIIIA toxin at pH 2.2-3.5 is described by two transitions overlapping by temperatures, indicating the presence of two domains.
authors.forename: O I
authors.initials: OI
authors.lastname: Loseva
authors.forename: M D
authors.initials: MD
authors.lastname: Kirkitadze
authors.forename: A P
authors.initials: AP
authors.lastname: Dobritsa
authors.forename: S A
authors.initials: SA
authors.lastname: Potekhin
mesh_terms: D001413:Bacillus thuringiensis / Q000737:chemistry*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000737:chemistry*; D001427:Bacterial Toxins; D002152:Calorimetry, Differential Scanning; D004731:Endotoxins / Q000737:chemistry*; D006460:Hemolysin Proteins; D017434:Protein Structure, Tertiary; D013816:Thermodynamics
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis
vernacular_title: Termodinamicheskiĭ analiz domennoĭ organizatsii toksinov Bacillus thuringiensis.