Abstract
Giardia intestinalis is a single-cell eukaryotic microorganism, regarded as one of the earliest divergent eukaryotes and thus an attractive model to study the evolution of regulatory systems. Giardia has two different forms throughout its life cycle, cyst and trophozoite, and changes from one to the other in response to environmental signals. The two differentiation processes involve a differential gene expression as well as a quick and specific protein turnover that may be mediated by the ubiquitin/proteasome system. The aim of this work was to search for unreported components of the ubiquitination system and to experimentally demonstrate their expression in the parasite and during the two differentiation processes. We found activity of protein ubiquitination in G. intestinalis trophozoites and analyzed the transcription of the ubiquitin gene, as well as that of the activating (E1), conjugating (E2), and ligase (E3) ubiquitin enzymes during encystation and excystation. A constant ubiquitin expression persisted during the parasite’s differentiation processes, whereas variation in transcription was observed in the other genes under study.
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Acknowledgment
We are thankful to Sandra Melo, Paula Hernández, Vanessa Gómez, Eliana Calvo, Carlos Niño, and Javier Escobar, members of the LIBBIQ, for helpful comments. This project received grants from the “Instituto para el Desarrollo de la Ciencia ‘Francisco José de Caldas’ (COLCIENCIAS)” -Project 1101.0514649 and the Universidad Nacional de Colombia (División de Investigaciones Bogotá, DIB). The experiments described in this paper comply with Colombian current laws on the matter.
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Gallego, E., Alvarado, M. & Wasserman, M. Identification and expression of the protein ubiquitination system in Giardia intestinalis . Parasitol Res 101, 1–7 (2007). https://doi.org/10.1007/s00436-007-0458-2
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DOI: https://doi.org/10.1007/s00436-007-0458-2