1978 — 1980 |
Dean, Donald |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Establishment of a Bacillus Genetic Stock Center |
0.915 |
1980 — 2004 |
Dean, Donald |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Maintenance of the Bacillus Genetic Stock Center |
0.915 |
1989 — 1996 |
Dean, Donald H |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Functional Domains of Bacillus Thuringiensis Endotoxin
Bacillus thuringiensis is a potent microbial insecticide that is widely used to control agricultural pests, and mosquitoes and blackflies which are vectors of human diseases. The active insecticidal components are the delta-endotoxins which vary in specificity, but are believed to have similar modes of action. They are processed from the protoxin form to active toxins by proteases in the insect midguts. The active toxin binds to receptors and causes cytolysis by forming a pore or ion channel. The overall goal of this proposal is to understand in detail the biochemical mechanisms of action of the protein toxins in their interaction with the receptor protein and their functions of membrane insertion and ion channel activity. The specific aims of the present proposal are to identify the amino acids involved in receptor binding and ion channel functions of insecticidal toxins. Molecular, genetic, biochemical, and electrophysiological techniques such as site-directed mutagenesis, chemical modification, voltage clamping, and patch clamping will be used to probe toxin function. Knowledge gained from this project will provide an understanding of the mode of action of insecticidal crystal proteins in order to design more specific and more potent toxins against insect pests. The long range goal is to use this information to design better biopesticides against insect vectors of human disease.
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1 |
1997 — 2001 |
Dean, Donald H |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Functinal Domains of Baccillus Thuringiensis Endotoxins
Bacillus thuringiensis is a microbial insecticide that is widely used to control numerous insects, including agricultural pests; and, mosquitoes and blackflies, vectors of human diseases. The active components are the insecticidal crystal proteins or Cry toxins. These insecticidal proteins may be manipulated by genetic and protein engineering to alter and improve their activity. The overall goal of this project is to investigate in detail the binding of several Cry toxins to a known receptor and improve the insecticidal activity by improving the binding to the receptor. The specific aims are to identify the amino acid residues on the Cry toxins that interact with the receptor and to experimentally alter these residues to identify which substituted residues enhance binding and toxicity. This will be accomplished by the genetic technique of site-directed mutagenesis. The components on the receptor that are responsible for interaction with the toxin will also be determined biochemically. The proposed research employs a model system consisting of a cry toxins of known structure as a well characterized receptor. When the basic understanding of toxin-receptor interaction is obtained, this may used to improve Cry toxins against the mosquito.
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1 |
2003 — 2007 |
Dean, Donald H |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Functional Domains of Bacillus Thuringiensis Endotoxins
DESCRIPTION (provided by the applicant): Bacillus thuringiensis is a microbial insecticide that is widely used to control insects, including mosquitoes and black flies. The long-range goal of this project is to investigate the binding and mechanism of action of several mosquitocidal proteins against key pestiferous mosquito species, Anopheles gambiae, Aedes aegypti and Culex quinquefaciatus. The main mosquitocidal toxins of interest are the toxins of B. thuringiensis var. israelensis (Bti), Cry4Aa, Cry4Ab and Cry11Aa. Other mosquitocidal toxins, Cry11Ba, Cry19Aa and Cry2Aa, will also be investigated. The hypothesis to be tested is that these toxins bind to specific receptors on the mosquito midgut as recognized in model insect-toxin studies (the Lepidoptera-toxin paradigm); i.e., an array of mosquito midgut proteins (cadherin-like and aminopeptidases) and glycoproteins bind the toxins; and, that domains II and Ill of the are the interacting binding epitopes. A corollary hypothesis is that the reduced ability of mosquitoes to develop resistance to Bti is due to a combination of toxins (Cry4Aa, Cry4Ab and Cry11Aa) each of which binds to a unique receptor or non-competing binding site. The specific aims of the proposal are: (1) Test the competition, saturation and irreversible binding of Cry4Aa, 4Ba, 11Aa, 11Ba, 19Aa and 2Aa toxins to mosquito BBMV and purified receptors. New mosquitocidal activity has been introduced into Cry4Ba (Culex activity) and 19Aa (Aedes activity). The mechanistic basis for these new activities will be investigated. (2) Examine the mechanism of action of mosquitocidal of these toxins, in comparison to the Lepidoptera toxins paradigm; specifically, to define the binding epitopes of these toxins to brush border membrane vesicles (BBMV) of the mosquitoes Aedes aegypti, Anopheles gambiae and Culex quinquefasciatus. (3) Examine the nature of mosquito midgut receptors in relation to what has been learned from Lepidoptera receptor paradigm; specifically, to identify the specific binding of these mosquitocidal Cry proteins on aminopeptidases, cadherin-like proteins, glycoproteins and other potential receptors of these mosquitoes.
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1 |