Copper trafficking in Trypanosoma cruzi: the transcriptional response of candidates to balance toxicity and recruitment

Abstract

Trypanosoma cruzi (Chagas disease) depends on acquiring nutrients and cofactors, like copper (Cu), from its hosts. Cu is essential for aerobic organisms, but it can also be toxic, so its transport and storage must be regulated. In the present study, we characterized the effects of changes in Cu availability on growth, intracellular ion content, and oxygen consumption. Our results show that Cu is essential for epimastigote proliferation and for metacyclogenesis, while intracellular amastigotes suffered from Cu stress during infection. We identify several genes potentially involved in Cu metabolism among which orthologs of the conserved P-type Cu ATPases involved in Cu export and loading of secreted enzymes were found and named TcCuATPase. TcCuATPase transcription is regulated during infective stages and by Cu availability in epimastigotes. No homologs were identified for the high affinity importer CTR1 instead we propose that the iron transport TcIT a ZIP family transporter is involved in Cu uptake based on its transcriptional response to Cu. Further canonical Cu targets (based on homology to yeast and mammals) such as the iron reductase TcFR and the cupro-oxidase TcFet3 are up regulated during infective stages and under intracellular Cu stress. We also demonstrated that Cu, iron, and heme metabolisms are related. In sum, Cu metabolism is essential in T. cruzi life cycle. Even though cytosolic Cu-chaperons are still missing, we propose a model for Cu transport and intracellular distribution in T. cruzi including conserved factors such as TcCuATPase and others such as TcFR and TcIT playing novel functions.