start-ver=1.4
cd-journal=joma
no-vol=104
cd-vols=
no-issue=
article-no=
start-page=8789
end-page=8799
dt-received=
dt-revised=
dt-accepted=
dt-pub-year=2020
dt-pub=20200911
dt-online=
en-article=
kn-article=
en-subject=
kn-subject=
en-title=
kn-title=Channel-pore cation selectivity is a major determinant of Bacillus thuringiensis Cry46Ab mosquitocidal activity
en-subtitle=
kn-subtitle=
en-abstract=
kn-abstract=Cry46Ab from Bacillus thuringiensis TK-E6 is a new mosquitocidal toxin with an aerolysin-type architecture, and it is expected to be used as a novel bioinsecticide. Cry46Ab acts as a functional pore-forming toxin, and characteristics of the resulting channel pores, including ion selectivity, have been analyzed. However, the relationship between channel-pore ion selectivity and insecticidal activity remains to be elucidated. To clarify the effects of charged amino acid residues on the ion permeability of channel-pores and the resulting insecticidal activity, in the present study, we constructed Cry46Ab mutants in which a charged amino acid residue within a putative transmembrane β-hairpin region was replaced with an oppositely charged residue. Bioassays using Culex pipiens mosquito larvae revealed that the mosquitocidal activity was altered by the mutation. A K155E Cry46Ab mutant exhibited toxicity apparently higher than that of wild-type Cry46Ab, but the E159K and E163K mutants exhibited decreased toxicity. Ions selectivity measurements demonstrated that the channel pores formed by both wild-type and mutant Cry46Abs were cation selective, and their cation preference was also similar. However, the degree of cation selectivity was apparently higher in channel pores formed by the K155E mutant, and reduced selectivity was observed with the E159K and E163K mutants. Our data suggest that channel-pore cation selectivity is a major determinant of Cry46Ab mosquitocidal activity and that cation selectivity can be controlled via mutagenesis targeting the transmembrane β-hairpin region.
en-copyright=
kn-copyright=

en-aut-name=HayakawaTohru
en-aut-sei=Hayakawa
en-aut-mei=Tohru
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=1
ORCID=

en-aut-name=MiyazakiMidoka
en-aut-sei=Miyazaki
en-aut-mei=Midoka
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=2
ORCID=

en-aut-name=HaradaSyoya
en-aut-sei=Harada
en-aut-mei=Syoya
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=3
ORCID=

en-aut-name=AsakuraMami
en-aut-sei=Asakura
en-aut-mei=Mami
kn-aut-name=
kn-aut-sei=
kn-aut-mei=
aut-affil-num=4
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=5
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 Interdisciplinary Science and Engineering in Health Systems, Okayama 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=

affil-num=5
en-affil=Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University
kn-affil=
en-keyword=Bacillus thuringiensis TK-E6
kn-keyword=Bacillus thuringiensis TK-E6
en-keyword=Cry46Ab toxin
kn-keyword=Cry46Ab toxin
en-keyword=Culex pipiens mosquito larvae
kn-keyword=Culex pipiens mosquito larvae
en-keyword=Site-directed mutagenesis
kn-keyword=Site-directed mutagenesis
en-keyword=Electrophysiologic analysis
kn-keyword=Electrophysiologic analysis
END