Characterization of Trypanosoma cruzi cysteine transport mechanisms and its adaptive regulation

CANEPA, GASPAR; BOUVIER, LEON; MIRANDA, MARIANA; UTTARO AD; PEREIRA, CA

FEMS MICROBIOLOGY LETTERS

Elsevier

Año: 2009 vol. 292 p. 27 - 32

0378-1097

L-Cysteine and methionine are unique amino acids that act as sulfur donors in allorganisms. In the specific case of Trypanosomatids, L-cysteine is particularlyrelevant as a substrate in the synthesis of trypanothione. Although it can besynthesized de novo, L-cysteine is actively transported in Trypanosoma cruziepimastigote cells. L-Cysteine uptake is highly specific; none of the amino acidsassayed yield significant differences in terms of transport rates. L-Cysteine istransported by epimastigote cells with a calculated apparent Km of 49.5 mM and aVmax of about 13 pmol min1 per 107 cells. This transport is finely regulated byamino acid starvation, extracellular pH, and between the parasite growth phases.In addition, L-cysteine is incorporated post-translationally into proteins, suggestingits role in iron–sulfur core formation. Finally, the metabolic fates of L-cysteinewere predicted in silico.