The apicoplast: a parasite’s symbiont

The endosymbiotic capture of a red alga brought photosynthesis to a previously heterotrophic protist, and marked the birth of a now very diverse new branch of the eukaryotic tree of life. Among the many plastid-bearing descendants of this event are the Apicomplexa, a phylum of obligate animal parasites. These include the causative agents of important diseases like malaria and toxoplasmosis. The apicomplexan plastid, or apicoplast, has experienced dramatic changes in function, organization and protein content as Apicomplexa adapted from photosynthesis to parasitism. In this chapter we outline the broad strokes of the organelle’s remarkable evolutionary history and follow how these changes shaped its biology and metabolism