The role of Plasmodium falciparum acyl-coenzyme A synthetase 10 in fatty acid acquisition and lipid synthesis

During the asexual blood stage, malaria parasites synthesize large quantities of lipids to support their rapid proliferation. Exogenous fatty acids obtained from host plasma are activated for lipid synthesis by parasite acyl-coenzyme A synthetases (ACSs). Of the twelve Plasmodium falciparum ACS homologs, ACS10 has emerged as a key blood-stage enzyme. Here, we sought to define the role of ACS10 in fatty acid acquisition and lipid synthesis during asexual development. To accomplish this, we have employed fatty acid alkyne probes of parasite lipid synthesis together with selective depletion of ACS10 in a conditional knockdown parasite line. This approach revealed that ACS10 is required for efficient incorporation of 16- to 20-carbon unsaturated fatty acid alkynes and a 20-carbon, saturated fatty acid alkyne into the major parasite phospholipids and neutral lipids. In contrast, shorter saturated fatty acid alkynes were either unaffected by ACS10 depletion or were hyper-incorporated into parasite lipids. ACS10 knockdown elicited a profound deformation of the food vacuole, which was likely caused by an imbalance of saturated and unsaturated fatty acids in parasite lipids. To promote the discovery and characterization of ACS inhibitors, we have established a fatty acid alkyne-based approach for identifying compounds that target ACS10 as their primary mode of action.