An active glucosylceramide synthase in epimastigote forms of Trypanosoma cruzi.

DUSCHAK VILMA G.,; LANDONI MALENA,; GARAVAGLIA PATRICIA; COUTO A.S..

Iguazú- Argentina

Congreso; XL Annual meeting SAIB 2004,; 2004

Soc. Arg. de Bioquímica y Biología Molecular

AN ACTIVE GLUCOSYLCERAMIDE SYNTHASE IN EPIMASTIGOTE FORMS OF TRYPANOSOMA CRUZI. Vilma G.Duschak1,Malena Landoni2, Patricia Garavaglia1 and   A.S. Couto2. 1Instituto Nacional de Parasitología, Dr. Mario Fatala Chabén, Anlis, Ministerio de Salud Y Ambiente. 2CIHIDECAR-Depto. Q. Orgánica, FCEyN, UBA. email: vduschak@yahoo.com.es Biosynthesis of glycosphingolipids involves the sequential action of glycosyltransferases and has been assumed that these enzymes are functionally organized in Golgi. However, the key step involves the transfer of glucose from UDP-glucose to ceramide catalyzed by a UDP-Glucose:glucosylceramide transferase (EC 2.4.1.80; glucosylceramide synthase (GCS) to form glucosylceramide, the precursor of most higher order glycosphingolipids. Here we report the presence of the glucosylceramide transferase involved in the biosynthesis of glycosphingolipids in epimastigote forms of T. cruzi CL strain, showing the  characterization of other byproducts of the enzyme reaction (such as acylated glucosylceramide). In addition, in order to get some insight on the subcellular location of this enzyme, immunoelectron microscopy techniques were used. Ultrathin sections were stained with anti-human GCS 5.1 antibody (a kind gift of Drs.Marks and Pagano) followed by gold conjugated secondary antibody. The results obtained showed label not only in the Golgi apparatus as expected, but also in microdomains all around the parasite membrane indicating its location may be posible in  lipid rafts.