Restriction of intramolecular movements within the Cry1Aa toxin molecule of Bacillus thuringiensis through disulfide bond engineering.
Disulfide bridges were introduced into CrylAa, a Bacillus thuringiensis lepidopteran toxin, to stabilize different protein domains including domain I alpha-helical regions thought to be involved in membrane integration and permeation. Bridged mutants could not form functional ion channels in lipid bilayers in the oxidized state, but upon reduction with beta-mercaptoethanol, regained parental toxin channel activity. Our results show that unfolding of the protein around a hinge region linking domain I and II is a necessary step for pore formation. They also suggest that membrane insertion of the hydrophobic hairpin made of alpha-helices 4 and 5 in domain I plays a critical role in the formation of a functional pore.
Schwartz
J L
JL
Biotechnology Research Institute, National Research Council of Canada, Montreal, Quebec. Jean-Louis.Schwartz@bri.nrc.ca
Juteau
M
M
Grochulski
P
P
Cygler
M
M
Préfontaine
G
G
Brousseau
R
R
Masson
L
L
D001413:Bacillus thuringiensis / Q000378:metabolism*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001427:Bacterial Toxins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D004220:Disulfides / Q000737:chemistry / Q000378:metabolism*; D004731:Endotoxins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006460:Hemolysin Proteins; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D015202:Protein Engineering
D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004220:Disulfides; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis