Abstract
Autophagy is a degradative process largely conserved among eukaryotes. Apicomplexan parasites are single-celled eukaryotes with a very significant impact on health and economy. Although, these eukaryotes can apparently generate autophagosome-like structures in particular stress conditions, they seem to possess a rather rudimentary autophagy machinery. On the other hand, very unusually, in these parasites the autophagy protein ATG8 localizes constitutively to the apicoplast, a nonphotosynthetic plastid that has important metabolic functions. The enigmatic function of ATG8 (and related proteins) in relation to this organelle is likely independent from canonical autophagy and yet it is very important for the survival of apicomplexan parasites. Further understanding of these original roles for ATG proteins might thus bring insights into new possible therapeutic avenues to combat these parasites. Moreover, it remains to be clarified how and when this specialization occurred in these early-branching eukaryotes, and if this new function was accompanied by a loss of the canonical autophagy pathway.