Non conserved residues between Cqm1 and Aam1 mosquito α-glucosidases are critical for the capacity of Cqm1 to bind the Binary toxin from Lysinibacillus sphaericus

Ferreira, Lígia Maria; Romão, Tatiany Patrícia; Nascimento, Nathaly Alexandre do; Costa, Maria da Conceição Mendes Ferreira da; Rezende, Antônio Mauro; Neto, Osvaldo P. de Melo; Silva-Filha, Maria Helena Neves Lobo

doi:10.1016/j.ibmb.2014.04.004

Cited by 18 publications

(9 citation statements)

References 36 publications

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“…The α-glucosidases from mosquito larvae have been poorly characterized [ 153 ]. However, the catalytic activity of the native or recombinant Cqm1 was demonstrated, indicating its potential ability to participate in carbohydrate digestion [ 154 , 155 , 156 ].…”

Section: Toxins and Mode Of Actionmentioning

confidence: 99%

Bacterial Toxins Active against Mosquitoes: Mode of Action and Resistance

Silva-Filha

Romão

Rezende

et al. 2021

Toxins

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Larvicides based on the bacteria Bacillus thuringiensis svar. israelensis (Bti) and Lysinibacillus sphaericus are effective and environmentally safe compounds for the control of dipteran insects of medical importance. They produce crystals that display specific and potent insecticidal activity against larvae. Bti crystals are composed of multiple protoxins: three from the three-domain Cry type family, which bind to different cell receptors in the midgut, and one cytolytic (Cyt1Aa) protoxin that can insert itself into the cell membrane and act as surrogate receptor of the Cry toxins. Together, those toxins display a complex mode of action that shows a low risk of resistance selection. L. sphaericus crystals contain one major binary toxin that display an outstanding persistence in field conditions, which is superior to Bti. However, the action of the Bin toxin based on its interaction with a single receptor is vulnerable for resistance selection in insects. In this review we present the most recent data on the mode of action and synergism of these toxins, resistance issues, and examples of their use worldwide. Data reported in recent years improved our understanding of the mechanism of action of these toxins, showed that their combined use can enhance their activity and counteract resistance, and reinforced their relevance for mosquito control programs in the future years.

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Section: Toxins and Mode Of Actionmentioning

confidence: 99%

Bacterial Toxins Active against Mosquitoes: Mode of Action and Resistance

Silva-Filha

Romão

Rezende

et al. 2021

Toxins

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“…However, the native Aam1 did not bind to the recombinant BinB protein . Recently, nonconserved residues between Cqm1 and Aam1 have been shown to be responsible for the BinB binding of Cqm1 …”

Section: Introductionmentioning

confidence: 98%

“…A receptor of binary toxin in Culex pipiens has been identified as a GPI‐anchored maltase, Cpm1 ( C. pipiens Maltase 1), whereas its ortholog in Anopheles gambiae has been named Agm3 ( A. gambiae Maltase 3) . However, the presence of a Cpm1 ortholog is not sufficient condition for Bin sensitivity, as shown by the Bin‐refractory mosquito Aedes aegypti . The A. aegypti gene encoding a Cpm1/Cqm1 orthologue, named Aam1, is expressed as a midgut GPI‐anchored α‐glucosidase.…”

Section: Introductionmentioning

confidence: 99%

Crystal structure of BinB: A receptor binding component of the binary toxin from Lysinibacillus sphaericus

et al. 2014

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The binary toxin (Bin), produced by Lysinibacillus sphaericus, is composed of BinA (42 kDa) and BinB (51 kDa) proteins, which are both required for full toxicity against Culex and Anopheles mosquito larvae. Specificity of Bin toxin is determined by the binding of BinB component to a receptor present on the midgut epithelial membranes, while BinA is proposed to be a toxic component. Here, we determined the first crystal structure of the active form of BinB at a resolution of 1.75 Å. BinB possesses two distinct structural domains in its N- and C-termini. The globular N-terminal domain has a β-trefoil scaffold which is a highly conserved architecture of some sugar binding proteins or lectins, suggesting a role of this domain in receptor-binding. The BinB β-rich C-terminal domain shares similar three-dimensional folding with aerolysin type β-pore forming toxins, despite a low sequence identity. The BinB structure, therefore, is a new member of the aerolysin-like toxin family, with probably similarities in the cytolytic mechanism that takes place via pore formation.

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“…So far, studies have shown that the Bin toxin binds these receptors through the N‐terminal region of its BinB subunit , and specific residues essential for this interaction have been identified . Within Cqm1, an 183‐residue segment within its N‐terminal half has also been shown to be required for this interaction .…”

Section: Introductionmentioning

confidence: 99%

Co‐selection and replacement of resistance alleles to Lysinibacillus sphaericus in a Culex quinquefasciatus colony

et al. 2015

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The Cqm1 a-glucosidase, expressed within the midgut of Culex quinquefasciatus mosquito larvae, is the receptor for the Binary toxin (Bin) from the entomopathogen Lysinibacillus sphaericus. Mutations of the Cqm1 a-glucosidase gene cause high resistance levels to this bacterium in both field and laboratory populations, and a previously described allele, cqm1 REC , was found to be associated with a laboratory-resistant colony (R2362). This study described the identification of a novel resistance allele, cqm1 REC-2 , that was co-selected with cqm1 REC within the R2362 colony. The two alleles display distinct mutations but both generate premature stop codons that prevent the expression of midgut-bound Cqm1 proteins. Using a PCR-based assay to monitor the frequency of each allele during long-term maintenance of the resistant colony, cqm1 REC was found to predominate early on but later was replaced by cqm1 REC-2 as the most abundant resistance allele. Homozygous larvae for each allele were then generated that displayed similar high-resistance phenotypes with equivalent low levels of transcript and lack of protein expression for both cqm1 REC and cqm1 REC-2 . In progeny from a cross of homozygous individuals for each allele at a 1 : 1 ratio, analyzed for ten subsequent generations, cqm1 REC showed a higher frequency than cqm1 REC-2 . The replacement of cqm1 REC by cqm1 REC-2 observed in the R2362 colony, kept for 210 generations, indicates changes in fitness related to traits that are unknown but linked to these two alleles, and constitutes a unique example of evolution of resistance within a controlled laboratory environment.

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Non conserved residues between Cqm1 and Aam1 mosquito α-glucosidases are critical for the capacity of Cqm1 to bind the Binary toxin from Lysinibacillus sphaericus

Cited by 18 publications

References 36 publications

Bacterial Toxins Active against Mosquitoes: Mode of Action and Resistance

Bacterial Toxins Active against Mosquitoes: Mode of Action and Resistance

Crystal structure of BinB: A receptor binding component of the binary toxin from Lysinibacillus sphaericus

Co‐selection and replacement of resistance alleles to Lysinibacillus sphaericus in a Culex quinquefasciatus colony

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