Trypanosoma brucei aquaglyceroporins facilitate the uptake of arsenite and antimonite in a pH dependent way.

BACKGROUND: Trypanosoma brucei is a primitive parasitic protozoan that thrives in diverse environments such as the midgut of the tsetse fly and the blood of a mammalian host. For an adequate adaptation to these environments, the parasite's aquaglyceroporins play an important role. METHODS AND RESULTS: In order to test their ability to transport trivalent arsenic and antimony, we expressed the three known Trypanosoma brucei aquaglyceroporins (TbAQPs) in the heterologous systems of yeast null aquaporin mutant and Xenopus laevis oocytes. For both expression systems, we found a pH dependent intracellular accumulation of As(III) or Sb(III) mediated by all of the three TbAQPs, with the exception of TbAQP1-As(III) uptake. Additionally, we observed that Trypanosoma brucei aquaglyceroporins allow the passage of As(III) in both directions. CONCLUSION: Taken together, these results demonstrated that T. brucei aquaglyceroporins can serve as entry routes for As(III) and Sb(III) into the parasitic cell, and that this uptake is pH sensitive. Therefore, aquaporins of protozoan parasites may be considered useful as a vehicle for drug delivery.

Kinetoplastida: model organisms for simple autophagic pathways?

Phylogenetic analyses based on defined proteins or different RNA species have revealed that the order kinetoplastida belongs to the early-branching eukaryotes and may thus contain organisms in which complex cellular events are easier to analyze. This view was further supported by results from a bioinformatic survey that suggested that nearly half of the autophagy-related proteins existent in yeast are missing in trypanosomatids. On the other hand, these organisms have evolved a highly sophisticated machinery to escape from the different host immune-response strategies and have learned to cope with extremely variable environmental conditions by morphological and functional reorganization of the cell. For both the stress response and the differentiation processes, autophagy seems to be an indispensable prerequisite. So far autophagy has not been systematically investigated in trypanosomatids. Here we present technical information on how to handle the different parasites belonging to this order and give an overview of the current status of autophagy research in these organisms.