Molecular Transport of IFT Complexes in Leishmania

Abstract/Summary: Leishmania are obligate, intracellular parasites that are the causative agent of leishmaniasis—a disease responsible for an estimated 1 million global infections each year, with ~70,000 fatalities. Therapeutics are limited, and are generally restricted to general use, anti-protozoan drugs that lack efficacy, thus presenting considerable threat to public health worldwide. Leishmania entry into host cells is mediated by flagella/cilia: a hair-like organelle that protrudes from the pathogen body and beats to create motion—allowing Leishmania to swim and attach to the host cell. Flagella use an active transport system called intraflagellar transport (IFT) to shuttle proteins between the base and tip. Because flagella do not contain ribosomes or proteasomes, IFT regulates all proteins inside the flagellum and thus maintains flagellum-dependent transduction pathways—including those required for Leishmania pathogenesis. Motor proteins move cargo along doublet microtubules that span the length of each flagellum. Cargo is linked to these motors via adaptor proteins: large multi-subunit complexes—including IFT-A, IFT-B, and the BBSome—that polymerize along the microtubules to form intraflagellar trains (IFT trains). However, IFT train assembly and transport mechanisms are poorly understood. The proposed work investigates two major components of IFT: assembly and in situ interactions of the IFT-B complex (Aim 1) and the interaction between the BBSome and the IFT-A complex (Aim 2).