Structure-Function Studies of Novel Insecticidal Toxins

University Of Connecticut Health Center, Farmington CT

Investigators

Abstract

9983243 King A key factor in determining agricultural output is the reduction in crop yield due to insect pests and viruses. Insect pests have traditionally been controlled by application of chemical pesticides. However, pesticide management in the USA and elsewhere is becoming increasingly complicated due to the evolution of insect resistance to classical chemical pesticides, growing community awareness of the environmental damage caused by many agrochemicals, and the exploitation of pesticide residuals in export crops and livestock as trade barriers. Thus, new "environmentally friendly" strategies are required to combat highly resistant insect species. One option is to engineer insect-specific toxins into plants, as exemplified by the engineering of genes encoding insecticidal d-endotoxins from the soil bacterium Bacillus thuringiensis into a variety of agriculturally important cultivars. A potentially more selective method is to use insect-specific viruses as vectors to deliver toxins to a restricted number of target species without harming beneficial insects and predators of the targeted pest. There are only a limited number of well-characterized insect-specific biopesticides that lend themselves to genomic approaches. Hence this PI has begun a program with specific aims to discover and characterize insect-specific peptide toxins that are suitable for engineering into plants and viruses. In this project he proposes to further characterize the action and structure-activity relationships in three families of insect-specific toxins that he and his co-workers have isolated from the venom of the Australian funnel-web spider: the w-atracotoxins, d-atracotoxins, and N-atracotoxins. They propose to determine the three-dimensional structure and analyze the mode of action of two paralytic insecticidal toxins that they recently isolated from the same spider. The ultimate goal is to develop each of these toxins to the point where they can be safely engineered into plants and insect-specific viruses.