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Evidence that free GPI glycolipids are essential for growth of Leishmania mexicana
Author(s) -
Ilgoutz Steven C.,
Zawadzki Jody L.,
Ralton Julie E.,
McConville Malcolm J.
Publication year - 1999
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/18.10.2746
Subject(s) - lipophosphoglycan , dolichol , biology , mannose , leishmania mexicana , glycolipid , biochemistry , glycoconjugate , glycoprotein , glycosylation , mutant , gene , biosynthesis , leishmania , genetics , parasite hosting , leishmania donovani , leishmaniasis , visceral leishmaniasis , world wide web , computer science
The cell surface of the parasitic protozoan Leishmania mexicana is coated by glycosylphosphatidylinositol (GPI)‐anchored glycoproteins, a GPI‐anchored lipophosphoglycan and a class of free GPI glycolipids. To investigate whether the anchor or free GPIs are required for parasite growth we cloned the L.mexicana gene for dolichol–phosphate–mannose synthase (DPMS) and attempted to create DPMS knockout mutants by targeted gene deletion. DPMS catalyzes the formation of dolichol–phosphate mannose, the sugar donor for all mannose additions in the biosynthesis of both the anchor and free GPIs, except for a α1‐3‐linked mannose residue that is added exclusively to the free GPIs and lipophosphoglycan anchor precursors. The requirement for dolichol–phosphate–mannose in other glycosylation pathways in L.mexicana is minimal. Deletion of both alleles of the DPMS gene ( lmdpms ) consistently resulted in amplification of the lmdpms chromosomal locus unless the promastigotes were first transfected with an episomal copy of lmdpms , indicating that lmdpms , and possibly GPI biosynthesis, is essential for parasite growth. As evidence presented in this and previous studies indicates that neither GPI‐anchored glycoproteins nor lipophosphoglycan are required for growth of cultured parasites, it is possible that the abundant and functionally uncharacterized free GPIs are essential membrane components.