Plant homologs of the Plasmodium falciparum chloroquine-resistance transporter, PfCRT, are required for glutathione homeostasis and stress responses.
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.
Maughan
Spencer C
SC
Institute of Biotechnology, University of Cambridge, Cambridge CB2 1QT, United Kingdom. smaughan@venrock.com
Pasternak
Maciej
M
Cairns
Narelle
N
Kiddle
Guy
G
Brach
Thorsten
T
Jarvis
Renee
R
Haas
Florian
F
Nieuwland
Jeroen
J
Lim
Benson
B
Müller
Christopher
C
Salcedo-Sora
Enrique
E
Kruse
Cordula
C
Orsel
Mathilde
M
Hell
Rüdiger
R
Miller
Anthony J
AJ
Bray
Patrick
P
Foyer
Christine H
CH
Murray
James A H
JA
Meyer
Andreas J
AJ
Cobbett
Christopher S
CS
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
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