L-myo-inositol 1-phosphate synthase from Entamoeba histolytica

L-myo-Inositol 1-phosphate synthase (I-1-P synthase) catalyses the primary reaction for the synthesis of inositol in a variety of prokaryotes, eukaryo tes and in the chloroplasts of algae and higher plants. Inositol is a precu rsor of essential macromolecules like membrane phospholipids, GPI anchor pr oteins and lipophosphoglycans, which play a determinant role in the pathoge nesis of protozoan parasites such as Leishmania and Entamoeba. However, the re is no report of I-1-P synthase or its gene from these organisms. The gen e INO1 coding for this enzyme was first cloned from Saccharomyces cervisiae and subsequently from several plants. Using molecular cloning techniques w e have isolated and characterised the INO1 gene coding for the enzyme I-1-P synthase from Entamoeba histolytica. Simultaneously, we have purified and characterised the native enzyme from E. histolytica trophozoites and the cl oned gene product from Escherichia coli. The gene product and the purified enzyme were both shown to be recognised by a heterologous anti-I-1-P syntha se antibody from the phytoflagellate Euglena gracilis. Phylogenetic analysi s of I-1-P synthase sequences from different eukaryotes suggest that it is highly conserved across species and the origin of this enzyme precedes the evolutionary divergence of modern eukaryotes. (C) 1999 Published by Elsevie r Science Ireland Ltd. All rights reserved.