Cry Toxins Use Multiple ATP-Binding Cassette Transporter Subfamily C Members as Low-Efficiency Receptors in Bombyx mori

Recent studies have suggested that ABC transporters are the main receptors of Cry toxins. However, the receptors of many Cry toxins have not been identified. In this study, we used a heterologous cell expression system to identify ABC transporter subfamily C members (BmABCCs) that function as recept...

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Published in:Biomolecules (Basel, Switzerland) Switzerland), 2024-02, Vol.14 (3), p.271
Main Authors: Adegawa, Satomi, Wang, Yonghao, Waizumi, Ryusei, Iizuka, Tetsuya, Takasu, Yoko, Watanabe, Kenji, Sato, Ryoichi
Format: Article
Language:English
Subjects:
ABC transporter
ABC transporters
Animals
ATP-Binding Cassette Transporters - genetics
ATP-Binding Cassette Transporters - metabolism
Bacillus thuringiensis Toxins
Bacterial Proteins - metabolism
binding affinity
Bombyx - metabolism
Bombyx mori
cry toxin
Cytotoxicity
Endotoxins
Hemolysin Proteins
Insecta - metabolism
low-efficiency receptor
Midgut
Multidrug Resistance-Associated Protein 2
Mutation
Proteins
Receptor mechanisms
Sensors
SPR analysis
Surface plasmon resonance
Toxins
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Summary:Recent studies have suggested that ABC transporters are the main receptors of Cry toxins. However, the receptors of many Cry toxins have not been identified. In this study, we used a heterologous cell expression system to identify ABC transporter subfamily C members (BmABCCs) that function as receptors for five Cry toxins active in Lepidopteran insects: Cry1Aa, Cry1Ca, Cry1Da, Cry8Ca, and Cry9Aa. All five Cry toxins can use multiple ABCCs as low-efficiency receptors, which induce cytotoxicity only at high concentrations. Surface plasmon resonance analysis revealed that the values between the toxins and BmABCC1 and BmABCC4 were 10 to 10 M, suggesting binding affinities 8- to 10,000-fold lower than those between Cry1Aa and BmABCC2, which are susceptibility-determining receptors for Cry1Aa. Bioassays in BmABCC-knockout silkworm strains showed that these low-efficiency receptors are not involved in sensitivity to Cry toxins. The findings suggest that each family of Cry toxins uses multiple BmABCCs as low-efficiency receptors in the insect midgut based on the promiscuous binding of their receptor-binding regions. Each Cry toxin seems to have evolved to utilize one or several ABC transporters as susceptibility-determining receptors.
ISSN:2218-273X
2218-273X
DOI:10.3390/biom14030271