Details

Autor(en) / Beteiligte

• Silber, Ariel M.
• Rojas, Robert L. Galvez
• Urias, Ursula
• Colli, Walter
• Alves, Maria Júlia Manso

Titel

Biochemical characterization of the glutamate transport in Trypanosoma cruzi

Ist Teil von

• International journal for parasitology, 2006-02, Vol.36 (2), p.157-163

Ort / Verlag

Oxford: Elsevier Ltd

Erscheinungsjahr

2006

Link zum Volltext

Quelle

MEDLINE

Beschreibungen/Notizen

• The role of amino acids in trypanosomatids goes beyond protein synthesis, involving processes such as differentiation, osmoregulation and energy metabolism. The availability of the amino acids involved in those functions depends, among other things, on their transport into the cell. Here we characterize a glutamate transporter from the human protozoan parasite Trypanosoma cruzi. Kinetic data show a single saturable system with a Km of 0.30 mM and a maximum velocity of 98.34 pmoles min −1 per 2×10 7 cells for epimastigotes and 20 pmoles min −1 per 2×10 7 cells for trypomastigotes. Transport was not affected by parasite nutrient starvation for up to 3 h. Aspartate, alanine, glutamine, asparagine, methionine, oxaloacetate and α-ketoglutarate competed with the substrate in 10-fold excess concentrations. Glutamate uptake was strongly dependent on pH, but not on Na + or K + concentrations in the extracellular medium. These data were consistent with the sensitivity of the system to the H + ionophore carbonyl cyanide p-trifluoromethoxyphenylhydrazone, suggesting that transport is driven by H + concentration gradient across the cytoplasmic membrane. The glutamate transport increased linearly with temperature in a range from 15 to 40 °C, allowing the calculation of an activation energy of 52.38 kJ/mol.