start-ver=1.4 cd-journal=joma no-vol=54 cd-vols= no-issue=4 article-no= start-page=389 end-page=398 dt-received= dt-revised= dt-accepted= dt-pub-year=2019 dt-pub=20190816 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Characterization of the channel-pores formed by Bacillus thuringiensis Cry46Ab toxin in planar lipid bilayers en-subtitle= kn-subtitle= en-abstract= kn-abstract= Cry46Ab from Bacillus thuringiensis TK-E6 is a new mosquitocidal toxin with aerolysin-type architecture, and has been shown that co-administration of Cry46Ab with other mosquitocidal Cry toxins results in synergistic toxicity against Culex pipiens Coquillett (Diptera: Culicidae) mosquito larvae. Cry46Ab, therefore, is expected to find use in improving the insecticidal activity of B. thuringiensis-based bioinsecticides. In the present study, the mode of action of Cry46Ab was explored by single-channel measurements of Cry46Ab channel-pores. The single-channel conductances of channel-pores formed in planar lipid bilayers by Cry46Ab were determined to be 31.8 +/- 2.7 pS in 150 mM NaCl and 24.2 +/- 0.7 pS in 150 mM CaCl2. Ion-selectivity measurements revealed that the channel-pores formed by Cry46Ab were cation selective. The permeability ratio of K+ to Cl-was approximately 4, and the preferences for cations were K+ > Na+, K+ > Ca2+, and Ca2+ > Na+. A calcein release assay using liposomes suggested that Cry46Ab influences the integrity of membrane vesicles. Formation of cation-selective channel-pores has been observed with other insecticidal Cry toxins that have structures distinct from those of Cry46Ab; the capability of forming such pores may be a property required of insecticidal toxins. en-copyright= kn-copyright= en-aut-name=SakakibaraAkira en-aut-sei=Sakakibara en-aut-mei=Akira kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=TakebeSo en-aut-sei=Takebe en-aut-mei=So kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=IdeToru en-aut-sei=Ide en-aut-mei=Toru kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=HayakawaTohru en-aut-sei=Hayakawa en-aut-mei=Tohru kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= affil-num=1 en-affil=Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University kn-affil= affil-num=2 en-affil=Graduate School of Biology-Oriented Science and Technology, Kindai University kn-affil= affil-num=3 en-affil=Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University kn-affil= affil-num=4 en-affil=Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University kn-affil= en-keyword=Bacillus thuringiensis kn-keyword=Bacillus thuringiensis en-keyword=Cry46Ab toxin kn-keyword=Cry46Ab toxin en-keyword=Planar lipid bilayer kn-keyword=Planar lipid bilayer en-keyword=Single-channel analysis kn-keyword=Single-channel analysis en-keyword=Calcein release assay kn-keyword=Calcein release assay END