Glycosomal phosphoenolpyruvate carboxykinase CRISPR/Cas9-deletion and its role in Trypanosoma cruzi metacyclogenesis and infectivity in mammalian host

Abstract

Trypanosoma cruzi, the causative agent of Chagas disease, possesses glycosomes - unique organelles that house key metabolic enzymes, several of which are promising therapeutic targets. Among them, phosphoenolpyruvate carboxykinase (PEPCK) plays a central role in succinic fermentation, the main pathway for NAD+ regeneration within the organelle. Using CRISPR/Cas9 editing, PEPCK gene was disrupted in T. cruzi, producing single- allele knockout epimastigotes (TcPEPCK-sKO) with reduced enzyme activity. This disruption impaired glucose consumption and mitochondrial respiration, particularly oxidative phosphorylation, reducing dependence on mitochondrial ATP production. To compensate, pyruvate phosphate dikinase was upregulated, increasing alanine production, possibly to maintain redox balance. Although TcPEPCK-sKO epimastigotes exhibited a minor reduction in growth, their differentiation (metacyclogenesis) and invasion were severely compromised. However, once inside the host cell, TcPEPCK-sKO amastigotes increased their replication, leading to enhanced trypomastigote production. The same was observed in in vivo infection, where TcPEPCK-sKO infection in IFN{gamma}-deficient mice caused uncontrolled parasitemia and severe pathology, highlighting the PEPCK critical role in host-pathogen interactions. However, an intact immune system effectively contained TcPEPCK-sKO infection. Taken together, our findings demonstrate that PEPCK is crucial for T. cruzi energy metabolism, enabling the parasite differentiation within the insect vector and controlling the infection of mammalian host cells.