Dolichol phosphate is a rate-limiting factor in mannosyl transferase activity of adult male worms of Schistosoma mansoni.

Abstract

The formation of mannolipid through catalysis by mannosyl transferase of adult females of Schistosoma mansoni was found to be 2-3-fold higher than male worms. In contrast, mannosyl transferase in immature females generated approximately the same amount of mannolipid as male worms, immature or not. Exogenous dolichol phosphate added to homogenates of male worms produced a stoichiometric increase in mannolipid formation. Saturating amounts of dolichol phosphate generated similar mannosyl transferase activities in male and female homogenates, showing that in S. mansoni, dolichol phosphate is the lipid intermediate in the glycosylation reaction and that this mannolipid is a rate-limiting substrate. Thin layer chromatography revealed that the mannolipid was identical in male and female worms. Adult males incubated with 14C-acetate synthesised several apolar compounds, one of which displayed a Rf identical to that of the mannolipid. When exposed to 14C-acetate treated males in vitro, untreated females were able to incorporate a compound, which partitioned in the same way as the mannolipid. The increased mannosyl transferase-dependent mannolipid formation in adult females may reflect a higher energy demand by these parasites, which is probably associated with oogenesis.