Glycosphingolipids in Plasmodium falciparum. Presence of an active glucosylceramide synthase.

COUTO, ALICIA S.; CAFFARO CAROLINA,; UHRIG M. LAURA,; KIMURA EMILIA,; PERES VALNICE J. ,; KATZIN ALEJANDRO M.,; NISHIOKA MASAE , .; NONAMI HIROSHI; ERRA-BALSELLS ROSA

EUROPEAN JOURNAL OF BIOCHEMISTRY

Blackwell Publishing Ltd

Lugar: Oxford; Año: 2004 vol. 271 p. 2204 - 2214

0014-2956

Malaria remains a major health problem especially in tropical and subtropical regions of the world, and therefore developing new antimalarial drugs constitutes an urgent challenge. Lipid metabolism has been attracting a lot of attention as an application for malarial chemotherapeutic purposes in recent years. However, little is known about glycosphingolipid biosynthesis in Plasmodium falciparum. In this report we describe for the first time the presence of an active glucosylceramide synthase in the intraerythrocyticstages of the parasite. Two different experiments, using UDP-[14C]glucose as donor with ceramides as acceptors, orUDP-glucose as donor and fluorescent ceramides as acceptors, were performed. In both cases, we found that the parasitic enzyme was able to glycosylate only dihydroceramide. The enzyme activity could be nhibited in vitro with low concentrations of D,L-threo-phenyl-2-palmitoylamino- 3-morpholino-1-propanol (PPMP). In addition, de novo biosynthesis of glycosphingolipids was shown by metabolic incorporation of [14C]palmitic acid and [14C]glucose in the three intraerythrocytic stages of the parasite. The structure of the ceramide, monohexosylceramide, trihexosylceramide and tetrahexosylceramide fractions was analysed by UVMALDI-TOF mass spectrometry. When PPMP was added to parasite cultures, a correlation between arrest of parasite growth and inhibition of glycosphingolipid biosynthesis was observed. The particular substrate specificity of the malarial glucosylceramide synthase must be added to the already known unique and amazing features of P. falciparum lipid metabolism; therefore this enzyme might represent a new attractive target for malarial chemotherapy.Plasmodium falciparum. In this report we describe for the first time the presence of an active glucosylceramide synthase in the intraerythrocyticstages of the parasite. Two different experiments, using UDP-[14C]glucose as donor with ceramides as acceptors, orUDP-glucose as donor and fluorescent ceramides as acceptors, were performed. In both cases, we found that the parasitic enzyme was able to glycosylate only dihydroceramide. The enzyme activity could be nhibited in vitro with low concentrations of D,L-threo-phenyl-2-palmitoylamino- 3-morpholino-1-propanol (PPMP). In addition, de novo biosynthesis of glycosphingolipids was shown by metabolic incorporation of [14C]palmitic acid and [14C]glucose in the three intraerythrocytic stages of the parasite. The structure of the ceramide, monohexosylceramide, trihexosylceramide and tetrahexosylceramide fractions was analysed by UVMALDI-TOF mass spectrometry. When PPMP was added to parasite cultures, a correlation between arrest of parasite growth and inhibition of glycosphingolipid biosynthesis was observed. The particular substrate specificity of the malarial glucosylceramide synthase must be added to the already known unique and amazing features of P. falciparum lipid metabolism; therefore this enzyme might represent a new attractive target for malarial chemotherapy.