Role of ¿1-pyrroline-5-carboxylate dehydrogenase supports mitochondrial metabolism and host-cell invasion of Trypanosoma cruzi

Proline is crucial for energizing critical events throughout the life cycle of Trypanosoma cruzi, the etiological agent of Chagas disease. The proline breakdown pathway consists of two oxidation steps, both of which produce reducing equivalents as follows: the conversion of proline to ¿1-pyrroline-5-carboxylate (P5C), and the subsequent conversion of P5C to glutamate. We have identified and characterized the ¿1-pyrroline-5-carboxy- late dehydrogenase from T. cruzi (TcP5CDH) and report here on how this enzyme contributes to a central metabolic pathway in this parasite. Size-exclusion chromatography, two-dimen- sional gel electrophoresis, and small angle x-ray scattering analysis of TcP5CDH revealed an oligomeric state composed of two subunits of six protomers. TcP5CDH was found to complement a yeast strain deficient in PUT2 activity, confirming the enzyme’s functional role; and the biochemical parameters (Km, kcat, and kcat/Km) of the recombinant TcP5CDH were determined, exhibiting values comparable with those from T. cruzi lysates. In addition, TcP5CDH exhibited mitochondrial staining during the main stages of the T. cruzi life cycle. mRNA and enzymatic activity levels indicated the up-regulation (6-fold change) of TcP5CDH during the infective stages of the parasite. The participation of P5C as an energy source was also demonstrated. Overall, we propose that this enzymatic step is crucial for the viability of both replicative and infective forms of T. cruzi

Aspectos Estruturais e Fitoquímicos de partes vegetativas de Costus spicatus (Jacq.) Sw. (Costaceae)

As folhas de Costus spicatus são amplamente empregadas na medicina popular para o tratamento de várias doenças entre elas: malária, hepatite e doença do aparelho urinário. O objetivo deste trabalho foi identificar aspectos da anatomia dos órgãos vegetativos (folhas, caules, raízes e rizomas) associados à triagem fitoquímica visando contribuir com informações relevantes para o desenvolvimento de estudos taxonômicos e farmacológicos. A análise anatômica por meio da microscopia óptica e de varredura evidenciou folha anfi-hipoestomática, com estômatos e tricomas tectores filamentosos simples. O mesofilo é constituído por parênquima clorofiliano, que se divide em duas regiões intercaladas por cordão de fibras e feixes vasculares. O caule é do tipo atactostélico como no rizoma. A raiz é poliarca. Os testes histoquímicos indicaram a presença de amido, proteínas estruturais, alcaloides, cristais de oxalato de cálcio. A prospecção química com extratos hidroalcoólico e aquoso constatou a presença de saponinas, taninos, alcaloides, compostos fenólicos e heterosídeos cianogênicos