Bombyx mori ABC transporter C2 structures responsible for the receptor function of Bacillus thuringiensis Cry1Aa toxin. (December 2017)

• Record Type: Journal Article
• Authors: Tanaka, Shiho; Endo, Haruka; Adegawa, Satomi; Iizuka, Ami; Imamura, Kazuhiro; Kikuta, Shingo; Sato, Ryoichi
• Is Part Of: Insect biochemistry and molecular biology. Volume 91(2017)
• Page Start: 44
• Page End: 54
• Publication Date: 2017-12
• Subjects: ABC transporter -- ABCC2 -- Bacillus thuringiensis -- Cry toxin -- Bombyx mori; ATP adenosine triphosphate -- ABC ATP-binding cassette -- ABCC2 ABC transporter subfamily C2 -- BBMV brush border membrane vesicle -- ECL extracellular loop -- NPV nuclear polyhedosis virus -- RNAi RNA interference; Insect biochemistry -- Periodicals; Insects -- Physiology -- Periodicals; Insects -- Molecular aspects -- Periodicals; Biochemistry -- Periodicals; Insectes -- Biochimie -- Périodiques; Insectes -- Composition -- Périodiques; Insectes -- Physiologie -- Périodiques; Insectes -- Aspect moléculaire -- Périodiques; Biochimie -- Périodiques; Biochemistry; Insect biochemistry; Insects -- Molecular aspects; Insects -- Physiology; Periodicals; 572.8157
• DOI: 10.1016/j.ibmb.2017.11.002
• Languages: English
• ISSNs: 0965-1748

Abstract

Abstract: Because Bombyx mori ABC transporter C2 (BmABCC2) has 1000-fold higher potential than B. mori cadherin-like protein as a receptor for Bacillus thuringiensis Cry1Aa toxin (Tanaka et al., 2013), the gate-opening ability of the latent pore under six extracellular loops (ECLs) of BmABCC2 was expected to be the reason for its higher potential (Heckel, 2012). In this study, cell swelling assays in Sf9 cells showed that BmABCC2 mutants lacking substrate-excreting activity retained receptor activity, indicating that the gate-opening activity of BmABCC2 is not responsible for Cry1Aa toxicity. The analysis of 29 BmABCC2 mutants demonstrated that 770 DYWL 773 of ECL 4 comprise a putative binding site to Cry1Aa. This suggests that specific toxicity of Cry1Aa toxin to a restricted range of lepidopteran insects is dependent on conservation and variation in the amino acid residues around 770 DYWL 773 of ECL 4 in the ABCC2. Graphical abstract: Dispensable (strip) and indispensable (red) structures for Cry1Aa-receptor function of BmABCC2. Highlights: The gating activity of ABCC2 is not required for function as Cry1A receptor. 770 DYWL 773 region in ECL 4 is involved in Cry1A binding. BmABCC2 excretes Ca 2+ indicator, X-Rhod-1 from cells.