title: Plant homologs of the Plasmodium falciparum chloroquine-resistance transporter, PfCRT, are required for glutathione homeostasis and stress responses.
abstract: In Arabidopsis thaliana, biosynthesis of the essential thiol antioxidant, glutathione (GSH), is plastid-regulated, but many GSH functions, including heavy metal detoxification and plant defense activation, depend on cytosolic GSH. This finding suggests that plastid and cytosol thiol pools are closely integrated and we show that in Arabidopsis this integration requires a family of three plastid thiol transporters homologous to the Plasmodium falciparum chloroquine-resistance transporter, PfCRT. Arabidopsis mutants lacking these transporters are heavy metal-sensitive, GSH-deficient, and hypersensitive to Phytophthora infection, confirming a direct requirement for correct GSH homeostasis in defense responses. Compartment-specific measurements of the glutathione redox potential using redox-sensitive GFP showed that knockout of the entire transporter family resulted in a more oxidized glutathione redox potential in the cytosol, but not in the plastids, indicating the GSH-deficient phenotype is restricted to the cytosolic compartment. Expression of the transporters in Xenopus oocytes confirmed that each can mediate GSH uptake. We conclude that these transporters play a significant role in regulating GSH levels and the redox potential of the cytosol.
authors.affiliation: Institute of Biotechnology, University of Cambridge, Cambridge CB2 1QT, United Kingdom. smaughan@venrock.com
authors.forename: Spencer C
authors.initials: SC
authors.lastname: Maughan
authors.forename: Maciej
authors.initials: M
authors.lastname: Pasternak
authors.forename: Narelle
authors.initials: N
authors.lastname: Cairns
authors.forename: Guy
authors.initials: G
authors.lastname: Kiddle
authors.forename: Thorsten
authors.initials: T
authors.lastname: Brach
authors.forename: Renee
authors.initials: R
authors.lastname: Jarvis
authors.forename: Florian
authors.initials: F
authors.lastname: Haas
authors.forename: Jeroen
authors.initials: J
authors.lastname: Nieuwland
authors.forename: Benson
authors.initials: B
authors.lastname: Lim
authors.forename: Christopher
authors.initials: C
authors.lastname: Müller
authors.forename: Enrique
authors.initials: E
authors.lastname: Salcedo-Sora
authors.forename: Cordula
authors.initials: C
authors.lastname: Kruse
authors.forename: Mathilde
authors.initials: M
authors.lastname: Orsel
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Hell
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Miller
authors.forename: Patrick
authors.initials: P
authors.lastname: Bray
authors.forename: Christine H
authors.initials: CH
authors.lastname: Foyer
authors.forename: James A H
authors.initials: JA
authors.lastname: Murray
authors.forename: Andreas J
authors.initials: AJ
authors.lastname: Meyer
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Cobbett
mesh_terms: D000818:Animals; D000962:Antimalarials / Q000494:pharmacology; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism*; D002104:Cadmium / Q000494:pharmacology; D002738:Chloroquine / Q000494:pharmacology; D004351:Drug Resistance; D005260:Female; D017343:Genes, Plant; D005978:Glutathione / Q000378:metabolism*; D006706:Homeostasis; D066298:In Vitro Techniques; D026901:Membrane Transport Proteins / Q000235:genetics* / Q000378:metabolism*; D008954:Models, Biological; D009154:Mutation; D009865:Oocytes / Q000378:metabolism; D030821:Plants, Genetically Modified; D010963:Plasmodium falciparum / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D015800:Protozoan Proteins / Q000235:genetics* / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013312:Stress, Physiological; D014981:Xenopus
chemical_list: D000962:Antimalarials; D029681:Arabidopsis Proteins; D026901:Membrane Transport Proteins; C416369:PfCRT protein, Plasmodium falciparum; D015800:Protozoan Proteins; D011994:Recombinant Proteins; D002104:Cadmium; D002738:Chloroquine; D005978:Glutathione