Conference Agenda

The intracellular apicomplexan parasite Toxoplasma gondii relies on both nutrient scavenging and biosynthetic pathways to acquire amino acids required for growth and survival. Our previous work identified the plasma membrane transporter TgApiAT2 as the primary glutamine transporter and, through a CRISPR-based screen, revealed that multiple amino acid biosynthetic pathways become fitness-conferring upon TgApiAT2 disruption, suggesting functional redundancy between uptake and synthesis. Here, we experimentally validate this model by generating double mutants lacking TgApiAT2 alongside key enzymes in amino acid biosynthesis. These mutants exhibit severe growth defects, demonstrating that parasites depend on compensatory mechanisms to maintain amino acid homeostasis. To further characterise TgApiAT2 function, we performed radiolabeled uptake assays, confirming that TgApiAT2 mediates the uptake of numerous non-essential amino acids. Together, our findings provide direct functional evidence for redundancy between amino acid uptake and synthesis in T. gondii, highlighting the metabolic flexibility that underpins parasite adaptation to variable host nutrient environments.