A comprehensive characterization of key organellar metabolic transporters in Apicomplexa to enter in the drug discovery pipeline

The phylum of Apicomplexa includes some of the most important parasites impacting human and veterinary health, such as Plasmodium and Toxoplasma. Plasmodium is the causative agent of malaria, a devastating parasitic infecting over estimates 228 million cases of malaria worldwide, causing 409 000 deaths in the year 2019, many under the age of 5 (WHO, World Malaria report 2020). Parasite’s resistance to most anti-malarial drugs makes it absolutely critical to identify and validate novel arsenal of targets for intervention. Members of this phylum replicate exclusively within eukaryotic cells and have evolved to retain or lose metabolic pathways that reflect their intracellular life style, niche and dependency on their host’s metabolic capabilities. These parasites display specific or alternate metabolic networks as most prominently documented by the metabolic pathways harbored in the vestigial plastid organelle, termed apicoplast and found essential in most apicomplexans. Understanding the parasite’s requirements for intracellular replication and the contribution of uptake of essential metabolites versus de novo synthesis is crucial to identify targets for compounds designed to inhibit and eradicate infections caused by these important human and animal pathogens. To identify novel drug targets, a detailed understanding of the metabolic needs of each life cycle stage is essential. A computational well-curated, stage-specific metabolic network of Toxoplasma gondii has been developed that integrates fitness data from CRISPR-based genome-wide screen (Sidik et al 2016) and gene expression data from various developmental stages available in ToxoDB (Krishnan et al 2020). Reconstruction of dependencies on plastid metabolic pathways and metabolites uptake allowed us identifying processes that explain why plastids have been retained or lost the phylum. The model highlighted to the instrumental parasite’s dependency for transporters to control the movement of ions, nutrients, metabolites, and waste products across the membranes for their survival. The major facilitator superfamily (MFS) members cover a broad range of solute transporters in microorganisms (Kumar, et al 2020). To fill the gap of transporters, we undertook a functional screen based on the 58 predicted MFS in T. gondii led to the identification and demonstration of a small set of crucial transporters for parasite survival, that are also conserved across the Apicomplexa. Remarkably, among them, TP1 and TP2 are localized to the apicoplast and conditional depletion of TP2 led to complete loss of the organelle. This project addresses the urgent need to develop new and effective anti-malarial molecules with limited off-target effects. Remarkably there is little redundancy in the Plasmodium transportome and solid evidence that transporters are likely to serve, or are already serving, as drug targets (Martin, 2020).

Project details

Drug-based Strategies
Product Development

May 2021 — Apr 2024

$269,793

India
Switzerland