Subcellular localization and dynamics of a digalactolipid-like epitope in Toxoplasma gondii.
Toxoplasma gondii is a unicellular parasite characterized by unique extracellular and intracellular membrane compartments. The lipid composition of subcellular membranes has not been determined, limiting our understanding of lipid homeostasis, control, and trafficking, a series of processes involved in pathogenesis. In addition to a mitochondrion, Toxoplasma contains a plastid called the apicoplast. The occurrence of a plastid raised the question of the presence of chloroplast galactolipids. Using three independent rabbit and rat antibodies against digalactosyldiacylglycerol (DGDG) from plant chloroplasts, we detected a class of Toxoplasma lipids harboring a digalactolipid-like epitope (DGLE). Immunolabeling characterization supports the notion that the DGLE polar head is similar to that of DGDG. Mass spectrometry analyses indicated that dihexosyl lipids having various hydrophobic moieties (ceramide, diacylglycerol, and acylalkylglycerol) might react with anti-DGDG, but we cannot exclude the possibility that more complex dihexosyl-terminated lipids might also be immunolabeled. DGLE localization was analyzed by immunofluorescence and immunoelectron microscopy and confirmed by subcellular fractionation. No immunolabeling of the apicoplast could be observed. DGLE was scattered in pellicle membrane domains in extracellular tachyzoites and was relocalized to the anterior tip of the cell upon invasion in an actin-dependent manner, providing insights on a possible role in pathogenetic processes. DGLE was detected in other Apicomplexa (i.e., Neospora, Plasmodium, Babesia, and Cryptosporidium).
Botté
Cyrille
C
Unité Mixte de Recherche 5168, Centre National de la Recherche Scientifique-Commissariat à l'Energie, Institut de Recherches en Technologies et Sciences pour le Vivant, 38058 Grenoble, France.
Saïdani
Nadia
N
Mondragon
Ricardo
R
Mondragón
Mónica
M
Isaac
Giorgis
G
Mui
Ernest
E
McLeod
Rima
R
Dubremetz
Jean-François
JF
Vial
Henri
H
Welti
Ruth
R
Cesbron-Delauw
Marie-France
MF
Mercier
Corinne
C
Maréchal
Eric
E
D000199:Actins / Q000378:metabolism; D000818:Animals; D000906:Antibodies / Q000276:immunology; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002736:Chloroplasts / Q000276:immunology / Q000378:metabolism; D000939:Epitopes / Q000276:immunology*; D038983:Galactolipids / Q000032:analysis / Q000276:immunology* / Q000378:metabolism*; D042541:Intracellular Space / Q000276:immunology* / Q000378:metabolism*; D013058:Mass Spectrometry; D016253:Microscopy, Immunoelectron; D011817:Rabbits; D051381:Rats; D018724:Spinacia oleracea / Q000276:immunology / Q000378:metabolism; D014122:Toxoplasma / Q000276:immunology* / Q000378:metabolism*
D000199:Actins; D000906:Antibodies; D000939:Epitopes; D038983:Galactolipids