Characterization of a Leishmania mexicana mutant defective in synthesis of free and protein-linked GPI glycolipids

Abstract

The cell surface of the promastigote stage of the protozoan parasite, Leishmania mexicana is coated by a number of glycosylphosphatidylinositol (GPI)-anchored proteins, a GPI-anchored lipophosphoglycan (LPG) and an abundant class of free GPIs, termed glycoinositolphospholipids (GIPLs). We have developed a new screen for isolating L. mexicana mutants that are defective in GPI biosynthesis, involving concanavalin A selection of a parental strain with a modified surface coat. One mutant was isolated that lacked the major GIPL species and mature GPI-protein anchor precursors, but synthesized normal levels of LPG anchor precursors. Based on analysis of apolar GIPLs that accumulate in this mutant ..