Manduca sexta cadherin (BtR1) and Bombyx mori aminopeptidase (BmAPN1) were transiently expressed on the surface of Drosophila S2 cells. Membranes from transfected cells bound Cry1A toxins with high-affinity. Fluorescent microscopy and flow cytometry were used to analyze toxin binding and cell mortality. Cry1Aa, Cry1Ab and Cry1Ac toxins, but not Cry1Ba, killed cells expressing BtR1 cadherin.
Lepidopteran APNs were also expressed on S2 cells then tested for toxin binding and toxicity. B. mori APN1 bound Cry1Aa specifically and caused cells to be killed by the toxin. Cry1Ac had no effect on cells expressing BmAPN1. Other expressed APNs did not function as receptors in the S2 cell system. The combination of insect cDNAs, the S2 cell expression system and fluorescence assays looks to be a promising system for investigating Cry toxin action.
Species 1: Lepidoptera Sphingidae Manduca sexta (tobacco hornworm)
Species 2: Lepidoptera Bombycidae Bombyx mori (silkworm)
Keywords: Cry1, receptor
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