PLoS Pathog. 15, e1007577 (2019)

The Apicomplexa are parasitic protozoa that scavenge essential nutrients from their hosts, generally through transporter proteins. However, very few apicomplexan transporters have been identified and characterized. Parker et al. now identify 66 new polytopic membrane proteins resembling transporters, which they dub ApiATs, in 6 different apicomplexan parasites. Of the 16 ApiATs from Toxoplasma gondii, 10 were expressed in the disease-causing tachyzoite stage of the life cycle, and those that were detectable by immunofluorescence all localized to the parasite periphery. Genetic disruption and mutational analysis implicated three as amino acid transporters, and radioligand quantitation and kinetic assays showed that TgApiAT5-3 exchanges a range of aromatic and large neutral amino acids, with a preference for l-tyrosine. Parasites lacking TgApiAT5-3 demonstrate an inability to transport aromatic amino acids, including l-phenylalanine, which is essential for T. gondii parasite growth in vitro, while work in mice indicates that TgApiAT5-3 is essential for virulence. This work underscores the ability of Apicomplexa to scavenge essential nutrients from their hosts using related transporters.

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Giel van Dooren