title: Expression and crystallization of an N-terminally activated form of the Bacillus thuringiensis Cry1Ca toxin.
abstract: When the active form of the Bacillus thuringiensis delta-endotoxin Cry1Ca was expressed in E. coli severe growth retardation was observed. The absence of a short peptide from the N-terminus of the protoxin was responsible for this effect. The introduction of a mutation at an amino acid previously reported as being involved in the initial stages of pore formation within the natural insect target partially abolished the growth retardation effect. We suggest that removal of the N-terminal peptide is a necessary step in toxin activation, the presence of this peptide preventing proper interaction of the toxin with the target membrane. Expression of the truncated toxin in Bacillus thuringiensis also prevented the formation of Cry1Ca crystals.
authors.affiliation: School of Biological Sciences. University of Sussex, Falmer, Brighton, United Kingdom.
authors.forename: T
authors.initials: T
authors.lastname: Kouskoura
authors.forename: C
authors.initials: C
authors.lastname: Tickner
authors.forename: N
authors.initials: N
authors.lastname: Crickmore
mesh_terms: D000595:Amino Acid Sequence; D001413:Bacillus thuringiensis / Q000235:genetics* / Q000378:metabolism; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D001427:Bacterial Toxins; D003460:Crystallization; D004731:Endotoxins / Q000235:genetics* / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D006460:Hemolysin Proteins; D009154:Mutation; D017384:Sequence Deletion
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis