Abstract
Trypanosoma cruzi is the aetiologic agent of Chagas disease. Our research group studies ribosomal RNA (rRNA) gene transcription and nucleolus dynamics in this species of trypanosomes. RPA31 is an essential subunit of RNA polymerase I (Pol I) whose presence is apparently restricted to trypanosomes. Using fluorescent-tagged versions of this protein (TcRPA31-EGFP), we describe its nuclear distribution during growth and metacyclogenesis. Our findings indicate that TcRPA31-EGFP alters its nuclear presence from concentrated nucleolar localization in exponentially growing epimastigotes to a dispersed granular distribution in the nucleoplasm of stationary epimastigotes and metacyclic trypomastigotes. These changes likely reflect a structural redistribution of the Pol I transcription machinery in quiescent cellular stages where downregulation of rRNA synthesis is known to occur. In addition, and related to the nuclear internalization of this protein, the presence of a classical bipartite-type nuclear localization signal was identified towards its C-terminal end. The functionality of this motif was demonstrated by its partial or total deletion in recombinant versions of the tagged fluorescent protein. Moreover, ivermectin inhibited the nuclear localization of the labelled chimaera, suggesting the involvement of the importin α/β transport system.
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Acknowledgements
We thank Juliana Herrera López and Karla López-Pacheco for technical assistance.
Funding
Israel Canela Pérez is a doctoral student from Programa de Doctorado en Ciencias Bioquímicas, Universidad Nacional Autónoma de Mexico and is a recipient of a fellowship from CONACyT (429279). We acknowledge financial funding from the Dirección General de Asuntos de Personal Académico, UNAM, through grant IN201616 to Roberto Hernández.
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Canela-Pérez, I., López-Villaseñor, I., Cevallos, A.M. et al. Nuclear distribution of the Trypanosoma cruzi RNA Pol I subunit RPA31 during growth and metacyclogenesis, and characterization of its nuclear localization signal. Parasitol Res 117, 911–918 (2018). https://doi.org/10.1007/s00436-018-5747-4
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DOI: https://doi.org/10.1007/s00436-018-5747-4