Icoplast isoprenoid7506511 | PNAS | April 30, 2013 | vol. 110 | no.Mprecursor biosynthesis is essential for the viability of red blood cell (RBC) stages of P. falciparum (12), indicating that some of these pathways cannot be bypassed by salvage of lipids from the host cell. The apicoplast is surrounded by four membranes, reflecting the complex evolutionary origin of this organelle (13). Essentially nothing is known about the lipid composition of these membranes or their biogenic origin. Apicoplasts contain a prokaryotic-like fatty acid synthase (FASII) complex as well as key enzymes involved in phospholipid biosynthesis, indicating that de novo synthesized fatty acids may be incorporated into apicoplast membrane lipids (9). However, recent studies have shown that apicoplast FASII is not essential for the growth of asexual RBC parasite stages, suggesting that apicoplast fatty acids and other lipids can be derived from other parasite lipid biosynthetic pathways and/or salvage from the host (for review, see refs.Oleuropein 6, 14, 15, 16). Consistent with this hypothesis, it has recently been reported that several apicoplast membrane proteins are delivered to the apicoplast via membrane vesicles derived from the endomembrane system (17, 18).Rivastigmine The plastids of photosynthetic plants and algae characteristically contain high levels of the galactoglycerolipids, monogalactosyldiacylglycerol (MGDG) and digalactosyldiacyglycerol (DGDG), which are essential for plastid function (19, 20). MGDG and DGDG are also abundant in Chromera velia (21), a photosynthetic alga closely related to Apicomplexa.PMID:35116795 Galactoglycerolipids and galactoceramides have previously been reported in Toxoplasma gondii (224), but these glycolipids have not been localized to the apicoplast and no genes encoding MGDG or DGDG galactosyltransferases have been identified in Apicomplexa. Whether the nonphotosynthetic plastids of Apicomplexa contain galactoglycerolipids therefore remains an open question. The isolation of apicoplasts and detailed analysis of their lipids in relation to those of whole parasites is an essential prerequisite for understanding the steps involved in apicoplast biogenesis and identifying lipids that are potentially important for apicoplast biosynthetic functions. Previous attempts to purify apicoplasts have been hampered by their physical connection to the mitochondrion (25). Here we report the use of an immunoisolationAuthor contributions: C.Y.B., Y.Y.-B., K.A.M., J.I.M., and G.I.M. designed research; C.Y.B., Y.Y.-B., T.W.T.R., K.A.M., J.I.M., T.P.S., M.K., and M.J.S. performed research; C.Y.B., Y.Y.-B., R.L.C., and P.K.C. contributed new reagents/analytic tools; C.Y.B., Y.Y.-B., T.W.T.R., J.I.M., M.K., E.M., M.J.M., and G.I.M. analyzed data; and C.Y.B., Y.Y.-B., M.J.M., and G.I.M. wrote the paper. The authors declare no conflict of interest. This article is a PNAS Direct Submission.To whom correspondence may be addressed: E-mail: cyrille.botte@gmail, malcolmm@ unimelb.edu.au, or [email protected]. M.J.M. and G.I.M. contributed equally to this work.This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10. 1073/pnas.1301251110/-/DCSupplemental.www.pnas.org/cgi/doi/10.1073/pnas.protocol similar to that used to purify subcellular organelles from other eukaryotes (26) for generating a highly enriched apicoplast fraction from blood stage trophozoites of P. falciparum. Lipidomic analysis of the purified organelles indicates that apicoplasts have.