The Cry4B toxin of Bacillus thuringiensis subsp. israelensis kills Permethrin-resistant Anopheles gambiae, the principal vector of malaria
| Autor: | Natalya B. Griko, Lee A. Bulla, Mohamed A. Ibrahim |
|---|---|
| Rok vydání: | 2013 |
| Předmět: |
Insecticides
endocrine system Mosquito Control Culex Anopheles gambiae Molecular Sequence Data Drug Resistance medicine.disease_cause General Biochemistry Genetics and Molecular Biology Microbiology Hemolysin Proteins Bacterial Proteins Species Specificity Bacillus thuringiensis Anopheles parasitic diseases medicine Animals Amino Acid Sequence Escherichia coli Permethrin Aedes Bacillus thuringiensis Toxins biology Toxin fungi Cadherins biology.organism_classification Insect Vectors Malaria Endotoxins Gastrointestinal Tract Protein Binding medicine.drug |
| Zdroj: | Experimental Biology and Medicine. 238:350-359 |
| ISSN: | 1535-3699 1535-3702 |
| Popis: | Resurgence of malaria has been attributed, in part, to the development of resistance by Anopheles gambiae, a principal vector of the disease, to various insecticidal compounds such as Permethrin. Permethrin, a neurotoxicant, is widely used to impregnate mosquito nets. An alternative strategy to control mosquitoes is the use of Bacillus thuringiensis subsp. israelensis (Bti) because there is no observable resistance in the field to the bacterium. Bti kills mosquitoes by targeting cadherin molecules residing in the midgut epithelium of larvae of the insect. Cry proteins (Cry4A, Cry4B, Cry10A and Cry11A) produced by the bacterium during the sporulation phase of its life cycle bind to the cadherin molecules, which serve as receptors for the proteins. These Cry proteins have variable specificity to a variety of mosquitoes, including Culex and Aedes as well as Anopheles. Importantly, selective mosquitocidal action is occasioned by binding of the respective Cry toxins to cadherins distinctive to individual mosquito species. Differential fractionation of the four Cry proteins from a novel Bti isolate (M1) and cloning and expression of their genes in Escherichia coli revealed that Cry4B is the only Cry protein that exerts insecticidal action against An. gambiae. Indeed, it does so against a Permethrin-resistant strain of the mosquito. The other three Cry proteins are ineffective. Multiple sequence alignments of the four Cry proteins revealed a divergent sequence motif in the Cry4B toxin, which most likely determines binding of the toxin to its cognate receptor, BT-R3, in An. gambiae and to its specific toxicity. A model showing Cry4B toxin binding to BT-R3 is presented. |
| Databáze: | OpenAIRE |
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