title: Characterization of Trypanosoma cruzi L-cysteine transport mechanisms and their adaptive regulation.
abstract: L-Cysteine and methionine are unique amino acids that act as sulfur donors in all organisms. In the specific case of Trypanosomatids, L-cysteine is particularly relevant as a substrate in the synthesis of trypanothione. Although it can be synthesized de novo, L-cysteine is actively transported in Trypanosoma cruzi epimastigote cells. L-Cysteine uptake is highly specific; none of the amino acids assayed yield significant differences in terms of transport rates. L-Cysteine is transported by epimastigote cells with a calculated apparent K(m) of 49.5 microM and a V(max) of about 13 pmol min(-1) per 10(7) cells. This transport is finely regulated by amino acid starvation, extracellular pH, and between the parasite growth phases. In addition, L-cysteine is incorporated post-translationally into proteins, suggesting its role in iron-sulfur core formation. Finally, the metabolic fates of Lcysteine were predicted in silico.
authors.affiliation: Laboratorio de Biología Molecular de Trypanosoma cruzi, Instituto de Investigaciones Médicas Alfredo Lanari, Consejo Nacional de Investigaciones Científicas y Té cnicas, Universidad de Buenos Aires, Buenos Aires, Argentina.
authors.forename: Gaspar E
authors.initials: GE
authors.lastname: Canepa
authors.forename: León A
authors.initials: LA
authors.lastname: Bouvier
authors.forename: Mariana R
authors.initials: MR
authors.lastname: Miranda
authors.forename: Antonio D
authors.initials: AD
authors.lastname: Uttaro
authors.forename: Claudio A
authors.initials: CA
authors.lastname: Pereira
mesh_terms: D000818:Animals; D003545:Cysteine / Q000378:metabolism*; D005786:Gene Expression Regulation; D007700:Kinetics; D008954:Models, Biological; D014349:Trypanosoma cruzi / Q000235:genetics* / Q000378:metabolism*
chemical_list: D003545:Cysteine