title: N-glycosylation influences the catalytic activity of mosquito α-glucosidases associated with susceptibility or refractoriness to Lysinibacillus sphaericus.
abstract: Cqm1 and Aam1 are α-glucosidases (EC 3.2.1.20) expressed in Culex quinquefasciatus and Aedes aegypti larvae midgut, respectively. These orthologs share high sequence similarity but while Cqm1 acts as a receptor for the Binary (Bin) insecticidal toxin from Lysinibacillus sphaericus, Aam1 does not bind the toxin, rendering Ae. aegypti refractory to this bacterium. Aam1 is heavily glycosylated, contrasting to Cqm1, but little is known regarding how glycosylation impacts on its function. This study aimed to compare the N-glycosylation patterns and the catalytic activities of Aam1 and Cqm1. Mutant proteins were generated where predicted Aam1 N-glycosylation sites (N-PGS) were either inserted into Cqm1 or abrogated in Aam1. The mutants validated four N-PGS which were found to localize externally on the Aam1 structure. These Aam1 and Cqm1 mutants maintained their Bin binding properties, confirming that glycosylation has no role in this interaction. The α-glucosidase activity of both proteins was next investigated, with Aam1 having a remarkably higher catalytic efficiency, influenced by changes in glycosylation. Molecular dynamics showed that glycosylated and nonglycosylated Aam1 models displayed distinct patterns that could influence their catalytic activity. Differential N-glycosylation may then be associated with higher catalytic efficiency in Aam1, enhancing the functional diversity of related orthologs.
authors.affiliation: Department of Entomology, Centro de Pesquisas Aggeu Magalhães/FIOCRUZ, Recife, PE 50740-465, Brazil.
authors.forename: Nathaly Alexandre do
authors.initials: NAD
authors.lastname: Nascimento
authors.affiliation: Department of Entomology, Centro de Pesquisas Aggeu Magalhães/FIOCRUZ, Recife, PE 50740-465, Brazil.
authors.forename: Lígia Maria
authors.initials: LM
authors.lastname: Ferreira
authors.affiliation: Department of Entomology, Centro de Pesquisas Aggeu Magalhães/FIOCRUZ, Recife, PE 50740-465, Brazil.
authors.forename: Tatiany Patrícia
authors.initials: TP
authors.lastname: Romão
authors.affiliation: Department of Entomology, Centro de Pesquisas Aggeu Magalhães/FIOCRUZ, Recife, PE 50740-465, Brazil.
authors.forename: Darleide Maria da Conceição
authors.initials: DMDC
authors.lastname: Correia
authors.affiliation: Department of Microbiology, Centro de Pesquisas Aggeu Magalhães/FIOCRUZ, Recife, PE 50740-465, Brazil.
authors.forename: Crhisllane Rafaele Dos Santos
authors.initials: CRDS
authors.lastname: Vasconcelos
authors.affiliation: Department of Microbiology, Centro de Pesquisas Aggeu Magalhães/FIOCRUZ, Recife, PE 50740-465, Brazil.
authors.forename: Antônio Mauro
authors.initials: AM
authors.lastname: Rezende
authors.affiliation: Instituto Oswaldo Cruz/FIOCRUZ, Rio de Janeiro, RJ 21045-900, Brazil.
authors.forename: Samara Graciane
authors.initials: SG
authors.lastname: Costa
authors.affiliation: Instituto Oswaldo Cruz/FIOCRUZ, Rio de Janeiro, RJ 21045-900, Brazil; Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular, Rio de Janeiro, RJ 21941-902, Brazil.
authors.forename: Fernando Ariel
authors.initials: FA
authors.lastname: Genta
authors.affiliation: Department of Microbiology, Centro de Pesquisas Aggeu Magalhães/FIOCRUZ, Recife, PE 50740-465, Brazil.
authors.forename: Osvaldo Pompílio
authors.initials: OP
authors.lastname: de-Melo-Neto
authors.affiliation: Department of Entomology, Centro de Pesquisas Aggeu Magalhães/FIOCRUZ, Recife, PE 50740-465, Brazil. Electronic address: mhneves@cpqam.fiocruz.br.
authors.forename: Maria Helena Neves Lobo
authors.initials: MHNL
authors.lastname: Silva-Filha
mesh_terms: D000330:Aedes / Q000201:enzymology*; D000818:Animals; D003465:Culex / Q000201:enzymology*; D006031:Glycosylation; D016987:Gram-Positive Rods; D056004:Molecular Dynamics Simulation; D000520:alpha-Glucosidases / Q000378:metabolism*
chemical_list: D000520:alpha-Glucosidases
keywords: Aam1; Aedes aegypti; Cqm1; Culex quinquefasciatus; Glucosidases; N-glycosylation