Investigating the role of Cry2Aa’s N terminus in its activity towards dipteran species Aedes aegypti

Alzahrani, Faisal (2022) Investigating the role of Cry2Aa’s N terminus in its activity towards dipteran species Aedes aegypti. Doctoral thesis (PhD), University of Sussex.

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Bacillus thuringiensis is known to produce pesticidal proteins that have been used to control a variety of insect species. Cry2Aa, a three-domain pore-forming toxin, has been shown to have activity against both lepidopteran and dipteran insects. In particular it has been shown to have activity against the yellow fever mosquito (Aedes aegypti) whereas the closely related protein, Cry2Ab, does not possess such activity. The specificity of these proteins to a particular insect has generally been associated with the binding of domains II and III to a particular receptor on the surface of midgut epithelial cells. Recent work however has shown that domain I of Cry2Aa heavily influences the activity of the protein to this mosquito, and that changing just four amino acids within the N-terminal region was enough to introduce this activity to Cry2Ab.This project sought to understand the role of domain I, and these four amino acids in particular, in the activity of Cry2A proteins against A. aegypti. Initially we discounted the hypothesis that this region was directly involved in receptor binding by demonstrating that it was removed during the proteolytic activation step. We then went on to show that it was whether or not the protein was cleaved around these four amino acids by the mosquito digestive enzymes that determined whether or not it would have activity against the insect. This led to a new hypothesis that cleavage of the protein in this region revealed a new epitope involved in receptor binding. This was tested by performing binding assays with different truncated forms of Cry2Aa which showed that the region of domain I between amino acids 49 and 144 was required for the binding of the protein to the midgut of A. aegypti.

Item Type: Thesis (Doctoral)
Schools and Departments: School of Life Sciences > Biochemistry
Subjects: Q Science > QL Zoology > QL0360 Invertebrates > QL0434 Arthropoda > QL0463 Insects > QL0531 Diptera (Flies)
R Medicine > RA Public aspects of medicine > RA0421 Public health. Hygiene. Preventive Medicine > RA0639 Transmission of disease
Depositing User: Library Cataloguing
Date Deposited: 07 Jun 2022 13:33
Last Modified: 07 Jun 2022 13:33

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