Biochemical characterization of the glutamate transport in Trypanosoma cruzi

Author(s)

Silber, Ariel M. ; Galvez Rojas, Robert L. ; Urias, Ursula ; Colli, Walter ; Alves, Maria Júlia Manso ^[5]

• Document type: Journal article
• Source: International Journal for Parasitology; v. 36, n. 2, p. 157-163, Feb. 2006.
• Field of knowledge: Biological Sciences - Biochemistry

Abstract

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, oil 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 2x10(7) cells for epimastigotes and 20 pmoles min(-1) per 2x10(7) cells for trypomastigotes. Transport was not affected by parasite nutrient starvation for up to 3 h. Aspartate, alanine, glutamine, asparagine, methionine, oxaloacetate and alpha-ketoglularate competed with the substrate in 10-fold excess concentrations. Glutamate uptake was strongly dependent on pH, but not oil 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 degrees C, allowing the calculation of an activation energy of 52.38 kJ/mol. (AU)

• FAPESP's process: 04/03303-5 - Interaction between Trypanosoma cruzi and host: binders, receptors and conditioners of intracellular development
• Grantee: Maria Julia Manso Alves
• Support Opportunities: Research Projects - Thematic Grants