A role for the Saccharomyces cerevisiae ATX1 gene in copper trafficking and iron transport.
The ATX1 gene of Saccharomyces cerevisiae was originally identified as a multi-copy suppressor of oxidative damage in yeast lacking superoxide dismutase. We now provide evidence that Atx1p helps deliver copper to the copper requiring oxidase Fet3p involved in iron uptake. atx1Delta null mutants are iron-deficient and are defective in the high affinity uptake of iron. These defects due to ATX1 inactivation are rescued by copper treatment, and the same has been reported for strains lacking either the cell surface copper transporter, Ctr1p, or the putative copper transporter in the secretory pathway, Ccc2p. Atx1p localizes to the cytosol, and our studies indicate that it functions as a carrier for copper that delivers the metal from the cell surface Ctr1p to Ccc2p and then to Fet3p within the secretory pathway. The iron deficiency of atx1 mutants is augmented by mutations in END3 blocking endocytosis, suggesting that a parallel pathway for intracellular copper trafficking is mediated by endocytosis. As additional evidence for the role of Atx1p in iron metabolism, we find that the gene is induced by the same iron-sensing trans-activator, Aft1p, that regulates CCC2 and FET3.
Lin
S J
SJ
Division of Toxicological Sciences, Department of Environmental Health Sciences, Johns Hopkins University School of Public Health, Baltimore, Maryland 21205, USA.
Pufahl
R A
RA
Dancis
A
A
O'Halloran
T V
TV
Culotta
V C
VC
D001693:Biological Transport, Active; D002352:Carrier Proteins; D027682:Cation Transport Proteins; D002453:Cell Cycle; D003300:Copper / Q000378:metabolism*; D000079922:Copper Transport Proteins; D000079923:Copper Transporter 1; D003600:Cytosol / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism*; D007501:Iron / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D008954:Models, Biological; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors / Q000378:metabolism
C090297:AFT1 protein, S cerevisiae; C093341:ATX1 protein, S cerevisiae; C092974:CCC2 protein, S cerevisiae; C490078:CTR1 protein, S cerevisiae; D002352:Carrier Proteins; D027682:Cation Transport Proteins; D000079922:Copper Transport Proteins; D000079923:Copper Transporter 1; D005656:Fungal Proteins; D008565:Membrane Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D003300:Copper; D007501:Iron