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N-terminal activation is an essential early step in the mechanism of action of Bacillus thuringiensis Cry1Ac insecticidal toxin
journal contributionposted on 2023-06-08, 09:27 authored by Alejandra Bravo, Jorge Sánchez, Thaleia Kouskoura, Neil CrickmoreNeil Crickmore
A variant form of the Bacillus thuringiensis Cry1Ac toxin that is not cleaved at the N terminus during proteolytic activation with trypsin was found to be incapable of forming pores in Manduca sexta brush border membrane vesicles in vitro and had reduced insecticidal activity in vivo. Binding studies indicated an altered binding pattern of the mutant toxin in that bound toxin could not be fully displaced by a high molar excess of fully trypsin-activated toxin. These results suggest that proteolytic removal of the N-terminal peptide of Cry1Ac is an important step in toxin activation.
JournalJournal of Biological Chemistry
Department affiliated with
- Biochemistry Publications
NotesNC directed this work, mutant proteins were produced at Sussex by Kouskoura and Crickmore with specialised assays performed by collaborators in Mexico. The work describes an important role for the N-terminus of the Bt toxin with implications for GM crops which express these toxins.
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