Toxoplasma gondii serine hydrolases regulate parasite lipid mobilization during growth and replication within the host
The intracellular protozoan parasite Toxoplasma gondii must scavenge cholesterol and other lipids from the host to facilitate intracellular growth and replication. Enzymes responsible for neutral lipid synthesis have been identified but there is no evidence for enzymes that catalyze lipolysis of cholesterol esters and esterified lipids. Here we characterize several T. gondii serine hydrolases with esterase and thioesterase activities that were previously thought to be depalmitoylating enzymes. We find they do not cleave palmitoyl thiol esters but rather hydrolyze short chain lipid esters. Deletion of one of the hydrolases results in alterations in levels of multiple lipids species. We also identify small molecule inhibitors of these hydrolases and show that treatment of parasites results in phenotypic defects reminiscent of parasites exposed to excess cholesterol or oleic acid. Together, these data characterize enzymes necessary for processing lipids critical for infection and highlight the potential for targeting parasite hydrolases for therapeutic applications. HighlightsO_LIBioinformatic and biochemical characterization of T. gondii serine hydrolases reveals substrate preference between enzymes with similar catalytic fold C_LIO_LIT. gondii serine hydrolases previously thought to be depalmitoylases are lipid metabolizing enzymes C_LIO_LIT. gondii lipid metabolism pathways utilize enzymes that are viable therapeutic targets C_LI