Cry toxin specificities of insect ABCC transporters closely related to lepidopteran ABCC2 transporters

In this study, we examined insect and human ABCC transporters closely related to the lepidopteran ABC transporter C2 (ABCC2), a powerful receptor for the Bacillus thuringiensis Cry toxin, for their responses to various Cry toxins. ABCC2 and the lepidopteran ABC transporter C3 (ABCC3) conferred cultured cells with susceptibility to a lepidopteran-specific Cry1Aa toxin but not to lepidopteran-specific Cry1Ca and Cry1 Da. One coleopteran ABCC transporter specifically responded to a coleopteran-specific Cry8Ca toxin. ABCC transporters from a dipteran insect and humans did not respond to any of the tested Cry toxins that are active to lepidopteran and coleopteran insects. These results yield important information for our understanding of insect specificity of Cry toxins and provide the first demonstration of a coleopteran ABCC transporter that serves as a Cry toxin receptor.