Functional Bacillus thuringiensis Cyt1Aa is necessary to synergize Lysinibacillus sphaericus Binary toxin against Bin-resistant and refractory mosquito species.

Functional Bacillus thuringiensis Cyt1Aa is necessary to synergize Lysinibacillus sphaericus Binary toxin against Bin-resistant and refractory mosquito species. Appl Environ Microbiol. 2020 Jan 31;: Authors: do Nascimento NA, Torres-Quintero MC, Molina SL, Pacheco S, Romão TP, Pereira-Neves A, Soberón M, Bravo A, Silva-Filha MHNL Abstract The Binary (Bin) toxin from Lysinibacillus sphaericus is effective to mosquito larvae but its utilization is threatened by the development of insect resistance. Bin toxin is composed by the BinB subunit required for binding to midgut receptors, and the BinA subunit that causes toxicity after cell internalization, mediated by BinB. Culex quinquefasciatus resistance to this toxin is caused by mutations that prevent expression of Bin toxin-receptors in the midgut. Previously, it was shown that the Cyt1Aa toxin, from Bacillus thuringiensis subsp. israelensis (Bti), restores Bin toxicity to Bin-resistant Cx. quinquefasciatus and to Aedes aegypti larvae, which is naturally devoid of functional Bin receptors. Our goal was to elucidate the mechanism involved in Cyt1Aa synergism with Bin in such larvae. In vivo assays showed that the mixture of Bin toxin, or its BinA subunit, with Cyt1Aa was effective to kill resistant larvae. However, no specific binding interaction between Cyt1Aa and the Bin toxin, or its subunits, was observed. The synergy between Cyt1Aa and Bin toxins is dependent on functional Cyt1Aa,...
Source: Applied and Environmental Microbiology - Category: Microbiology Authors: Tags: Appl Environ Microbiol Source Type: research