Characterization of α-Glucosidases From Lutzomyia longipalpis Reveals Independent Hydrolysis Systems for Plant or Blood Sugars

Abstract

Lutzomyia longipalpis is the main vector of Leishmania infantum and exploits different food sources during development. Adults have a diet rich in sugars, and females also feed on blood. The sugar diet is essential for maintaining longevity, infection, and Leishmaniasis transmission. Carbohydrases, including α-glucosidases, are the main enzymes involved in the digestion of sugars. In this context, we studied the modulation of α-glucosidase activities in different feeding conditions and compartments of Lutzomyia longipalpis females, in order to characterize in detail their roles in the physiology of this insect. All tissues showed activity against MUαGlu and sucrose, with highest activities in the midgut and crop. Activity was 1,000 times higher on sucrose than on MUαGlu. Basal activities were observed in non-fed insects; blood feeding induced activity in the midgut contents, and sugar feeding modulated activity in midgut tissues. α-glucosidase activity changed after female exposure to different sugar concentrations or moieties. α-glucosidases from different tissues showed different biochemical properties, with an optimum pH around 7.0–8.0 and K M between 0.37 and 4.7 mM, when MUαGlu was used as substrate. Using sucrose as substrate, the optimum pH was around 6.0, and K M ranges between 11 and 800 mM. Enzymes from the crop and midgut tissues showed inhibition in high substrate concentrations (sucrose), with K I ranging from 39 to 400 mM, which explains the high K M values found. Chromatographic profiles confirmed that different α-glucosidases are been produced in L. longipalpis in different physiological contexts, with the distinction of at least four α-glucosidases. The results suggest that some of these enzymes are involved in different metabolic processes, like digestion of plant sugars, digestion of blood glycoproteins or glycolipids, and mobilization of energetic storages during starvation.

Proteomics and ultrastructural analysis of Hermetia illucens (Diptera: Stratiomyidae) larval peritrophic matrix

“…Insect α-glucosidase is classified as family I. Family I α-glucosidase has four conserved regions, which can also be found in α-amylase, but there is no sequence similarity between them [ 63 ]. Carbohydrases are often used as targets for pesticides, such as amylases or glucosidase inhibitors [ 64 , 65 ].…”

Essential (Mg, Fe, Zn and Cu) and Non-Essential (Cd and Pb) Elements in Predatory Insects (Vespa crabro and Vespa velutina): A Molecular Perspective

“…This enzyme, which removes α-(1-6) linkages, detaches from glycogen units of glucose and is important for continued glycogen breakdown during insect flight [45]. Alpha-glucosidase catalyzes the hydrolysis of α-glucosidic bonds, releasing free glucose; this enzyme is present as a soluble form in the midgut lumen or bound to cell membranes and is important for the digestion of sucrose [46,47]. Trehalase is the enzyme that hydrolyses trehalose, a circulating disaccharide containing two D-glucose units in an α,α-(1-1) linkage, which plays a crucial role as a metabolic source of energy [48].…”

Schistocerca piceifrons piceifrons (Orthoptera: Acrididae) as a Source of Compounds of Biotechnological and Nutritional Interest

“…Many insect species are an important source of proteins, peptides, secondary metabolites, and polymers, such as silk, chitin, and chitosan used by the pharmaceutical and food industries (Milusheva and Rashidova 2017, Teramoto et al 2019). Since they have numerous metabolic and genetic adaptations to cope with diverse environments, mainly through the production of specialized molecules and enzymes (Dias et al 2015, Hardersen and Zapponi 2018, Da Costa et al 2019, Kannan et al 2019), insects are increasingly considered as an alternative source for discovering compounds of biotechnological interest (Seabrooks and Hu 2017). In this context, insect pests have been analyzed as biological material for their potential as sources of food and bioactive compounds.…”