Characterization of D-glucose transport in Trypanosoma rangeli

Like in other trypanosomatids D-glucose is a crucial source of energy to Trypanosoma rangeli, a non-pathogenic parasite that in Central and South America infects triatomine vectors and different mammalian species, including humans. In several trypanosome species, D-glucose transporters were already described and cloned. In this study, we characterized the D-glucose transport activity present in 2 life-stage forms of T. rangeli (epimastigotes and trypomastigotes) using D-[U-14C]glucose as substrate. Our results indicate that T. rangeli transports D-glucose with high affinity in both epimastigote (Km 30 microM) and trypomastigotes (Km 80 microM) life-forms. Both transport activities were inhibited by Cytochalasin B and Phloretin, indicating that probably D-glucose uptake in T. rangeli is mediated by facilitated diffusion of the sugar. Significant differences were observed between epimastigotes and trypomastigotes in relation to their affinity for D-glucose analogues, and the predicted amino acid sequence of a putative D-glucose transporter from T. rangeli (TrHT1) showed a larger identity with the T. cruzi D-glucose transporter encoded by the TcrHT1 gene than with other transporters already characterized in trypanosomatids.