Genome-Scale Identification of Essential Metabolic Processes for Targeting the Plasmodium Liver Stage

Summary Plasmodium gene functions in mosquito and liver stages remain poorly characterized due to limitations in the throughput of phenotyping at these stages. To fill this gap, we followed more than 1,300 barcoded P. berghei mutants through the life cycle. We discover 461 genes required for efficient parasite transmission to mosquitoes through the liver stage and back into the bloodstream of mice. We analyze the screen in the context of genomic, transcriptomic, and metabolomic data by building a thermodynamic model of P. berghei liver-stage metabolism, which shows a major reprogramming of parasite metabolism to achieve rapid growth in the liver. We identify seven metabolic subsystems that become essential at the liver stages compared with asexual blood stages: type II fatty acid synthesis and elongation (FAE), tricarboxylic acid, amino sugar, heme, lipoate, and shikimate metabolism. Selected predictions from the model are individually validated in single mutants to provide future targets for drug development.

Graphical Abstract

Highlights • 1,342 barcoded P. berghei knockout (KO) mutants analyzed for stage-specific phenotypes • Life-stage-specific metabolic models reveal reprogramming of cellular function • High agreement between blood/liver stage metabolic models and genetic screening data • Essential metabolic pathways for parasite development and mechanistic origin revealed

A genome-scale knockout screen identifies genes important for the entire malaria parasite life cycle and reveals growth bottlenecks in Plasmodium to establish infection in mammalian hosts.