Struggling to keep the batteries charged: energy metabolism as a drug target in kinetoplastid parasites

Abstract

The kinetoplastid parasites Trypanosoma brucei, T. cruzi, and Leishmania spp. are responsible for a variety of human and animal diseases including human African trypanosomiasis (HAT), Chagas disease, the leishmaniasis, and Nagana. Classified as Neglected Tropical Diseases, these diseases predominantly affect people from low-and middle-income countries where they are responsible for a significant burden of disease. Current therapies are insufficient and there is now an urgent need for novel drug candidates to improve clinical options. RNA editing ligase 1 (REL1) and phosphofructokinase (PFK) are key players in the energy and carbohydrate metabolism of these parasites. Once in the blood, T. brucei is completely reliant on glycolysis for ATP production. Further, RNAi knockdown experiments have confirmed the essentiality of both enzymes in the survival of T. brucei parasites. Several high throughput screening campaigns have identified a number of REL1 inhibitors in the Schnaufer lab. However, these inhibitors have not yet been validated as bona fide REL1 inhibitors and their mechanism of action is unclear. In addition, a novel series (CTCB) of small molecule allosteric inhibitors of trypanosome PFK have been developed in the Walkinshaw lab. These molecules inhibit glycolysis in Trypanosoma spp. by selective inhibition of parasite PFKs without inhibition of human PFKs. These CTCB compounds cross the blood brain barrier and a single oral dose is sufficient to cure parasitaemia in a haemolymphatic animal model of HAT. However, the on-target effect of these CTCB compounds on PFK in vivo in these parasites has not been experimentally studied. Therefore, the aims of the work presented here are three-fold: 1. Develop several biophysical assays to study REL1-ligand interactions. 2. Use in silico drug discovery tools to further aid REL1 hit discovery. 3. Support mode of action studies for CTCB-405, one of the most potent compounds in the CTCB series, by studying its effect on the metabolome of T. brucei and T. congolense using ion mobility mass spectrometry.