Mechanistic and Structural Insights into Intraflagellar Transport in Leishmania - Project Summary Trypanosomatid parasites are responsible for several human diseases including Chagas disease (Trypanosoma cruzi), African trypanosomiasis (Trypanosoma brucei), and leishmaniasis (various Leishmania species). These parasites critically depend on a single flagellum for motility, environmental sensing, and cell attachment. Disruptions in flagellar motility or intraflagellar transport (IFT) impair the ability of the parasite to survive in insect vectors or mammalian hosts. The flagellum is therefore essential for the parasite’s survival and pathogenicity, making IFT a potential therapeutic target. IFT involves the movement of cargo-laden megadalton complexes called IFT trains along the outer face of doublet microtubules within flagella. Recent cryo-electron tomography studies have elucidated the molecular architecture of IFT trains in green algae, but the conservation of IFT train structure, and their interactions with different cargo adaptors and the doublet microtubule tracks they travel along, remains unclear. We propose to use a genetically tractable Leishmania species, Leishmania tarentolae, as a model organism to address these questions. We propose a multidisciplinary approach that combines structural biology, live-cell imaging, proteomics, and high-throughput bioinformatic screens. Successful completion of this work will reveal the conserved and trypanosomatid- specific features of Leishmania IFT, identify new adaptor proteins that link polyubiquitinated proteins to IFT trains for export from flagella, and determine whether microtubule-associated proteins that bind the surface of doublet microtubules regulate IFT. Given that IFT is essential for the pathogenicity of trypanosomatids, this research may identify targets for the development of novel therapies for diseases that put millions at risk of infection globally.
