Toxoplasma gondii is an obligate intracellular apicomplexan parasite that, as many organisms, require iron as a cofactor to be used in many essential proteins. Excess iron can be toxic for the cells, meaning incorporation and storage are tightly regulated. The full mechanisms by which T. gondii responds to iron availability through infections and how iron is incorporated and driven into the mitochondria, where heme and Fe-S clusters are synthesized remain unknown. However, previous results have implicated the homolog of the yeast mitochondrial iron transporter Mrs3/4, named mitochondrial iron transporter (MIT)¹. MIT levels were seen to increase in the absence of the iron storage transporter VIT, suggesting a role for MIT in iron detoxification. Here we assessed the importance of the putative mitochondrial iron transporter (MIT) in T. gondii biology. Our preliminary results indicate that MIT transcript and protein level increases upon iron deprivation, suggesting that it may play a role on iron uptake by the mitochondria. Despite the prediction of essentiality, we were able to generate a knock-out line for MIT and started its characterization. We find that deletion of MIT causes significant growth defect in vitro when compared to WT parasites. This was seen both by plaque assay and in competition assays. Interestingly, excess iron fails to overcome this growth phenotype, demonstrating that MIT is not the primary route of iron detoxification in the parasite. Currently, we continue characterizing MIT-KO by analysing mitochondrial functions that may be compromised. Together, we show for the first time that MIT is important for T. gondii survival and iron homeostasis.

1- Aghabi, D., Sloan, M., Gill, G. et al. The vacuolar iron transporter mediates iron detoxification in Toxoplasma gondii. Nat Commun 14, 3659 (2023). https://doi.org/10.1038/s41467-023-39436-