INVESTIGADORES
UTTARO Antonio Domingo
congresos y reuniones científicas
Título:
Versatility of sterol biosynthesis during the lifecycle in a close unicellular relative of animals.
Autor/es:
NAJLE S.; MOLINA M.C.; UTTARO, ANTONIO D.
Lugar:
Rosario
Reunión:
Congreso; L Reunión anual de la SAIB; 2014
Resumen:
Sterols are essential for several physiological processes in eukaryotes. Here, we provide strong genetic and
biochemical evidence about the biphasic nature of the sterols metabolism in Capsaspora owczarzaki, a close
unicellular relative of metazoans. The life cycle of C. owczarzaki presents an amoeboid stage, a multicellular
aggregative stage and a cystic stage, assumed as a resistance form. The C. owczarzaki genome shows the presence of
a complete set of genes for the canonical biosynthesis pathway of ergosterol, the typical sterol of Fungi, as well as the
presence of an ortholog of the Rieske sterol C7(8)-desaturase, previously described by our group in the unrelated
ciliate species Tetrahymena thermophila. However, the sterols profile obtained by GC/MS suggests the cells are able
to convert exogenous cholesterol into ergosterol by using a novel pathway. This was further confirmed by
supplementation studies with radioactive precursors. Moreover, we demonstrate the lack of de novo sterol synthesis
during the amoeboid and aggregative stages. Nevertheless, we were able to detect de novo produced 7-
dehydrocholesterol in the cystic stage. Conversion of cholesterol into ergosterol involves the action of three enzymes
from the ergosterol canonical pathway, as well as the sterol C7(8)-desaturase. These findings are supported by
available transcriptomics data of the C. owczarzaki lifecycle.