Developmental modification of the lipophosphoglycan from Leishmania major promastigotes during metacyclogenesis

Lipophosphoglycan was isolated from the dividing, noninfective stage and from the nondividing metacyclic stage of Leishmania major promastigotes. The lipophosphoglycans were characterized by SDS-PAGE and by chromatographic and quantitative analysis of phosphatidylinositol-specific phospholipase C- and mild acid-generated fragments. The results revealed two stage-specific structural differences: (i) an increase in size of the metacyclic form of the glycoconjugate due to an approximate doubling in the number of its salient phosphorylated saccharide units; and concomitantly, (ii) a subtle compositional change in these units. Gas-liquid chromatographic analysis indicated that the phosphatidylinositol lipid anchor was developmentally conserved. These developmental modifications suggest important roles for the lipophosphoglycan which have not been previously considered, such as promoting complement resistance within the vertebrate host, and midgut attachment and release within the sand fly vector.