High-resolution spatial proteome map of Toxoplasma gondii extracellular tachyzoite

Apicomplexans, such as malaria-causing Plasmodium species, Toxoplasma, and Cryptosporidium, are parasitic protists that invade cells of virtually every animal, including humans. Despite the great burden on human healthcare and global economy, and the role in the environment, our understanding of the biology of these microorganisms is still very limited. Apicomplexans have evolved a complex cell architecture featuring a range of subcellular compartments, both common to all eukaryotes and unique to the phylum, that enable invasion into the host cell and exploiting its resources for growth and replication, rendering apicomplexans such remarkably successful parasites. In such an intricate subcellular landscape, protein function and location in the cell are tightly linked, which is why localising proteins in the cell is a major strategy in the apicomplexan research. Yet, the majority of proteins in model apicomplexans is unknown. In this project, a state-of-the-art spatial proteomics technology hyperLOPIT has been successfully adapted and applied to a model apicomplexan Toxoplasma gondii. Three independent hyperLOPIT experiments have been conducted on T. gondii strain RH extracellular tachyzoites, the invasive stage of the parasite's life cycle responsible for acute infection, providing the first cell-wide protein location atlas of any apicomplexan. This provides revolutionary insight into the apicomplexan cell organization and biology, including greatly expanded proteomes of secretory invasion organelles, the range of adaptive and regulatory responses of the organelles, and the subcellular distribution of evolutionary selection pressure, innovation, and conservation.