title: Active transport of glutamate in Leishmania (Leishmania) amazonensis.
abstract: Leishmania spp. are the causative agents of leishmaniasis, a complex of diseases with a broad spectrum of clinical manifestations. Leishmania (Leishmania) amazonensis is a main etiological agent of diffuse cutaneous leishmaniasis. Leishmania spp., as other trypanosomatids, possess a metabolism based significantly on the consumption of amino acids. However, the transport of amino acids in these organisms remains poorly understood with few exceptions. Glutamate transport is an important biological process in many organisms. In the present work, the transport of glutamate is characterized. This process is performed by a single kinetic system (K(m)=0.59+/-0.04 mM, V(max)=0.123+/-0.003 nmol/min per 20 x 10(6) cells) showing an energy of activation of 52.38+/-4.7 kJ/mol and was shown to be partially inhibited by analogues, such as glutamine, aspartate, alpha-ketoglutarate and oxaloacetate, methionine, and alanine. The transport activity was sensitive to the extracellular concentration of H(+) but not to Na(+) or K(+). However, unlike other amino acid transporters presently characterized, the treatment with specific ionophores confirmed the participation of a K(+), and not H(+) membrane gradient in the transport process.
authors.affiliation: Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Lisvane S
authors.initials: LS
authors.lastname: Paes
authors.forename: Robert L
authors.initials: RL
authors.lastname: Galvez Rojas
authors.forename: Anissa
authors.initials: A
authors.lastname: Daliry
authors.forename: Lucile M
authors.initials: LM
authors.lastname: Floeter-Winter
authors.forename: Marcel I
authors.initials: MI
authors.lastname: Ramirez
authors.forename: Ariel M
authors.initials: AM
authors.lastname: Silber
mesh_terms: D000818:Animals; D001693:Biological Transport, Active; D002412:Cations / Q000378:metabolism; D004791:Enzyme Inhibitors; D018698:Glutamic Acid / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007476:Ionophores / Q000494:pharmacology; D007700:Kinetics; D007891:Leishmania / Q000378:metabolism*
chemical_list: D002412:Cations; D004791:Enzyme Inhibitors; D007476:Ionophores; D018698:Glutamic Acid