Sulfoglycosphingolipids are biosynthesized by the intraerythrocytic stages of Plasmodium falciparum.

A. S. COUTO,; M. LANDONI,; E. KIMURA,; V. J. PERES,; M. NISHIOKA,; H. NONAMI,; R. ERRA.BALSELLS; A. M. KATZIN.

Honolulu, Hawaii

Congreso; Joint Meeting of the Society for Glycobiology and the Japanese Society for Carbohydrate Research; 2004

Plasmodium falciparum is one of the world´s most pathogenic microbes, it kills millions annually. Lipid metabolism has been attracting a lot of attention in the last years with respect to basic biology and applications for malaria chemoterapeutic purposes. Recently, we have shown the structural determination of malarial neutral glycosphingolipids. Among acidic glycolipids, gangliosides and sulfoglycolipids are usually found as membrane components, however, previous reports have shown that P. falciparum does not biosynthesize sialic acid. In this work we have performed metabolic incorporation of [14C]palmitic acid, [14C] glucose and Na235SO4  in the three intraerythrocytic stages of P. falciparum in order to determine the presence of sulfoglycolipids. Parasites metabolically labeled with [14C]palmitic acid or with [14C]glucose were extracted and fractionated by DEAE-Sephadex column chromatography. The acidic lipids were further subjected to alkaline hydrolysis and analysed. The three intraerythrocytic stages showed the presence of acidic components with both precursors. Moreover, when Na235SO4  was used as precursor, and the acidic components from the three labeled stages were analysed by TLC, at least two major labeled components SPf1 and SPf2, mainly present in the young trophozoite stage, were detected. Interestingly, both of them showed to migrate below the sulfogalactosylceramide (SM4s), the major sulfoglycolipid detected in uninfected red blood cells. In order to assure the sulfoglycosphingolipid nature of the labeled components [14C]palmitic acid labeled SPF1 was subjected to solvolysis. As expected, solvolysis of SPf1 produced a fast migrating component corresponding to the desulfated product. In addition, when another sample of SPf1 was subjected to methanolysis, a major component coincident with dihidrophingosine was obtained. Analogous results were obtained when the same treatments were performed on SPf2. In order to estimate the percentage of sulfatides among the glycolipids, the [14C]glucose incorporation was used. Sulfoglycolipids are minor components in P. falciparum, but interestingly, ring stage and trophozoites biosynthesize twice the amount (20%) of sulfoglycolipids that the schizont stage (10%). In order to make a better characterization of these sulfoglycosphingolipids, an analysis by UV-MALDI-TOF mass spectrometry was performed. Using nor-harmane as matrix in the negative ion mode, it was possible to determine the presence of a d:20 long chain base acylated with hydroxylated fatty acids (C12:0, C14:0). The presence of these sulfated compounds, active participants in adhesion processes in many systems may be related to the crucial role assigned to glycolipids during plasmodial life cycle  as well as with their action as potent disrupters of P. falciparum erythrocyte rosettes.