Journal Article

Kiss and spit metabolomics highlight the role of host purine metabolism during pathogen infection

Gallego-Lopez, Gina M, Olson, William J, Contreras Guzman, Emmanuel, Stevenson, David, Tibabuzo-Perdomo, Andres M, Knoll, Laura J, Skala, Melissa C, Amador-Noguez, Daniel, Leahy, James W, Lawrence, Grant

2026

Overview

Intracellular bacteria and protists rely on the host cell to supply many metabolites, but the mechanisms through which pathogens manipulate host metabolism to their benefit are not understood. Here, we demonstrate that when the obligate intracellular parasite secretes its rhoptry organelle contents into the host cytoplasm before invasion-a process called \"kiss and spit\"-host cell metabolite abundance is altered in nucleotide synthesis, the pentose phosphate pathway, glycolysis, and amino acid synthesis. U-13C6-labeling metabolomics confirmed that kiss and spit increased the flow of carbon through the pentose phosphate pathway and nucleotide synthesis. An increase in 2,3-bisphosphoglycerate abundance led us to investigate the activation of host cytosolic nucleosidase II (cN-II) to provide purines for the parasite. We found that manipulates the host cN-II enzyme to dephosphorylate GMP and IMP that it needs for replication. Furthermore, we found that the approved anti-cancer drug fludarabine, which inhibits cN-II, also inhibits replication. These results reveal host cell manipulation and highlight potential therapies for toxoplasmosis.IMPORTANCEA fundamental challenge in parasitology is understanding how intracellular parasites rapidly reprogram host metabolism to support replication. This study reveals that initiates profound metabolic reprogramming through a \"kiss-and-spit\" mechanism, secreting effector molecules without invasion. We demonstrate that specifically hijacks host cytosolic 5'-nucleotidase II (cN-II) by elevating 2,3-bisphosphoglycerate levels, which allosterically activates this enzyme to generate purines essential for parasite survival. Genetic deletion of host cN-II significantly impairs parasite replication, establishing cN-II as a critical host dependency factor. These findings have important implications for antiparasitic drug development while advancing our understanding of purine metabolism in apicomplexan parasites. More broadly, elucidating the molecular mechanism linking parasite effector secretion to specific host enzyme activation provides a framework for understanding metabolic manipulation across other intracellular pathogens.

• Publisher: ASM
• Subject: Clinical Microbiology and Infectious Diseases / Enzymes of Nucleotide Metabolism / Host Cell Invasion / Host Cell Manipulation / Host-Pathogen Interactions / Intracellular Survival / Microbial Pathogenesis and Immunology / Microbial Physiology and Genetics / Nucleotide Metabolism / Parasite Invasion Mechanisms / Parasitic Cell Invasion / Parasitic Infections / Parasitic Pathogenesis / Parasitic-Host Interactions / Parasitology / Purine Metabolism / Research Article / Toxoplasmosis / Zoonotic Parasitic Pathogens / Zoonotic Pathogens