期刊
MOLECULAR AND BIOCHEMICAL PARASITOLOGY
卷 185, 期 2, 页码 114-120出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.molbiopara.2012.07.009
关键词
Trypanosoma cruzi; Cysteine synthase; Cystathionine beta synthase; Cystathionine lyase; Transsulfuration pathway
资金
- Consejo Nacional de Investigaciones Investigaciones y Tecnicas (CONICET)
- Universidad de Buenos Aires (UBA)
- Agencia Nacional de Agencia Cientifica y Tecnologica (ANPCYT, Argentina)
- CONICET
Trypanosoma cruzi is expected to synthetize de novo cysteine by different routes, among which the two-step pathway involving serine acetyltransferase and cysteine synthase (CS) is comprised. Also, cystathionine beta synthase (CBS) might contribute to the de novo generation of cysteine in addition to catalyze the first step of the reverse transsulfuration route producing cystathionine. However, neither the functionality of CS nor that of cystathionine -y lyase (CGL) has been assessed. Our results show that T. cruzi CS could participate notably more actively than CBS in the de novo synthesis of cysteine. Interestingly, at the protein level T. cruzi CS is more abundant in amastigotes than in epimastigotes. Unlike the mammalian homologues, T. cruzi CGL specifically cleaves cystathionine into cysteine and is unable to produce H2S. The expression pattern of T. cruzi CGL parallels that of CBS, which unexpectedly suggests that in addition to the de novo synthesis of cysteine, the reverse transsulfuration pathway could be operative in the mammalian and insect stages. Besides, T. cruzi CBS produces H2S by decomposing cysteine or via condensation of cysteine with homocysteine. The latter reaction leads to cystathionine production, and is catalyzed remarkably more efficiently than the breakdown of cysteine. In T. cruzi like in other organisms, H2S could exert regulatory effects on varied metabolic processes. Notably, T. cruzi seems to count on stage-specific routes involved in cysteine production, the multiple cysteine-processing alternatives could presumably reflect this parasite's high needs of reducing power for detoxification of reactive oxygen species. (C) 2012 Elsevier B.V. All rights reserved.
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