The intracellular parasite Toxoplasma gondii depends on the synthesis of long chain and very long-chain unsaturated fatty acids not supplied by the host cell

Mol Microbiol. 2015 Mar 31. doi: 10.1111/mmi.13010. [Epub ahead of print]

 

Ramakrishnan S¹, Docampo MD, MacRae JI, Ralton JE, Rupasinghe T, McConville MJ, Striepen B.

 

Apicomplexa are parasitic protozoa that cause important human diseases including malaria, cryptosporidiosis and toxoplasmosis. The replication of these parasites within their target host cell is dependent on both salvage as well as de novo synthesis of fatty acids. In T. gondii, fatty acid synthesis via the apicoplast-localized FASII is essential for pathogenesis, while the role of two other fatty acid biosynthetic complexes remains unclear. Here we demonstrate that the ER-localized fatty acid elongation (ELO) is essential for parasite growth. Conditional knock-down of the non-redundant hydroxyacyl-CoA dehydratase and enoyl-CoA reductase enzymes in the ELO pathway severely repressed intracellular parasite growth. ¹³ C-glucose and ¹³ C-acetate labeling and comprehensive lipidomic analyses of these mutants showed a selective defect in synthesis of unsaturated long and very long chain fatty acids (LCFAs and VLCFAs) and depletion of phosphatidylinositol and phosphatidylethanolamine species containing unsaturated LCFAs and VLCFAs. This requirement for ELO pathway was by-passed by supplementing the media with specific fatty acids, indicating active, but inefficient import of host fatty acids. Our experiments highlight a gap between the fatty acid needs of the parasite and availability of specific fatty acids in the host cell that the parasite has to close using a dedicated synthesis and modification pathway.
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KEYWORDS:

Apicomplexa; Fatty acid synthesis; Plasmodium; fatty acid elongation; phospholipid

PMID:

25825226

[PubMed - as supplied by publisher]