Lipidomic analysis of Toxoplasma gondii tachyzoites rhoptries: further insights into the role of cholesterol.

摘要: Rhoptries are secretory organelles involved in the virulence of human pathogen Toxoplasma gondii. In present study we have used HPLC and capillary GLC to isolate quantify lipids from whole cells their purified rhoptries. This comparative lipidomic analysis revealed an enrichment cholesterol, sphingomyelin and, most all, saturated fatty acids These known, when membranes, contribute rigidity interestingly, fluorescence anisotropy measurements confirmed that rhoptry-derived membranes a lower fluidity than T. gondii cells. Moreover, although rhoptries were initially thought be highly enriched demonstrated cholesterol is proportions, provided additional evidence towards lack involvement rhoptry process host-cell invasion by parasite. Indeed, depleting content parasites did not prevent secretion protein-containing vesicles could still establish structure called moving junction, which necessary for invasion. Instead, crucial role host invasion, has already been [Coppens Joiner (2003) Mol. Biol. Cell 14, 3804-3820], might explained need cholesterol-rich region cell visualize at point contact with attached parasite, conditions where parasite motility was blocked.