Schistosoma mansoni: surface membrane isolation with lectin-coated beads

Area of Science:

• Parasitology
• Biochemistry
• Molecular Biology

Background:

• The surface membrane of adult Schistosoma mansoni worms plays a crucial role in parasite-host interactions and survival.
• Understanding the composition and organization of these membranes is essential for developing targeted anti-parasitic strategies.
• Selective isolation of membrane domains can provide insights into specific protein localization and function.

Purpose of the Study:

• To selectively isolate glycosylated surface membrane domains from adult Schistosoma mansoni worms.
• To compare the efficacy of immobilized lentil lectin with polycationic beads (Affi-Gel) for membrane isolation.
• To characterize the isolated membrane components, particularly tegumental phosphohydrolases.

Main Methods:

• Immobilization of Lens culinaris (lentil) lectin and Arachis hypogaea (peanut) lectin onto polyacrylamide beads.
• Comparison with membrane isolation using Affi-Gel beads.
• Analysis of bound fractions using enzyme activity assays (tegumental phosphohydrolases) and gel electrophoresis for polypeptide patterns.
• Solubilization of bound enzymes using detergent and competing sugars, followed by confirmation of glycosylation via affinity chromatography.

Main Results:

• Immobilized lentil lectin effectively interacted with surface membrane components, enriching tegumental phosphohydrolases.
• Gel electrophoresis revealed a more restricted polypeptide pattern for the lentil lectin-bound fraction compared to Affi-Gel.
• Immobilized peanut lectin was unsuccessful for isolating membrane material from the worm tegument.
• Glycosylation of solubilized enzyme markers was confirmed.
• Histochemical evidence and enzyme localization suggest active sites are near or within the cytoplasmic leaflet of tegumental membranes.

Conclusions:

• Immobilized lentil lectin is a suitable method for selective isolation of glycosylated membrane domains from adult Schistosoma mansoni.
• The study proposes a model for the double surface membrane complex, indicating some proteins may span both bilayers.
• These findings contribute to understanding Schistosoma mansoni membrane structure and offer potential targets for drug development.