title: PfNT2, a permease of the equilibrative nucleoside transporter family in the endoplasmic reticulum of Plasmodium falciparum.
abstract: The survival and proliferation of the obligate intracellular malaria parasite Plasmodium falciparum require salvage of essential purines from the host. Genetic studies have previously shown that the parasite plasma membrane purine permease, PfNT1, plays an essential function in the transport of all naturally occurring purine nucleosides and nucleobases across the parasite plasma membrane. Here, we describe an intracellular permease, PfNT2. PfNT2 is, like PfNT1, a member of the equilibrative nucleoside transporter family. Confocal and immunoelectron microscopic analyses of transgenic parasites harboring green fluorescent protein- or hemagglutinin-tagged PfNT2 demonstrated endoplasmic reticulum localization. This localization was confirmed by colocalization with the endoplasmic reticulum marker PfBiP. Using yeast as a surrogate system, we show that targeting PfNT2 to the plasma membrane of fui1Delta cells lacking the plasma membrane nucleoside transporter Fui1 confers sensitivity to the toxic nucleoside analog 5-fluorouridine. This study provides the first evidence of an intracellular purine permease in apicomplexan parasites and suggests a novel biological function for the parasite endoplasmic reticulum during malaria infection.
authors.affiliation: Section of Infectious Diseases, Yale School of Medicine, New Haven, CT 06512, USA.
authors.forename: Megan J
authors.initials: MJ
authors.lastname: Downie
authors.forename: Kamal
authors.initials: K
authors.lastname: El Bissati
authors.forename: April M
authors.initials: AM
authors.lastname: Bobenchik
authors.forename: Laura
authors.initials: L
authors.lastname: Nic Lochlainn
authors.forename: Alexander
authors.initials: A
authors.lastname: Amerik
authors.forename: Rachel
authors.initials: R
authors.lastname: Zufferey
authors.forename: Kiaran
authors.initials: K
authors.lastname: Kirk
authors.forename: Choukri
authors.initials: C
authors.lastname: Ben Mamoun
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004721:Endoplasmic Reticulum / Q000201:enzymology* / Q000648:ultrastructure; D004912:Erythrocytes / Q000469:parasitology; D005467:Floxuridine / Q000378:metabolism; D017930:Genes, Reporter; D006790:Host-Parasite Interactions; D006801:Humans; D016778:Malaria, Falciparum / Q000097:blood; D026901:Membrane Transport Proteins / Q000235:genetics* / Q000378:metabolism; D016253:Microscopy, Immunoelectron; D033703:Nucleoside Transport Proteins / Q000235:genetics* / Q000378:metabolism; D018512:Parasitemia / Q000097:blood; D010963:Plasmodium falciparum / Q000201:enzymology* / Q000235:genetics; D011401:Promoter Regions, Genetic; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism; D011687:Purines / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development; D014162:Transfection
chemical_list: D026901:Membrane Transport Proteins; D033703:Nucleoside Transport Proteins; D015800:Protozoan Proteins; D011687:Purines; D005467:Floxuridine