Cloning of Pichia pastoris Fet3: insights into the high affinity iron uptake system.
High-affinity iron uptake by yeast cells appears to require the presence of a complex formed on the plasma membrane by the multicopper oxidase Fet3 and the permease Ftr1 which work together to allow iron to enter safely inside the cell. The Pichia pastoris ferroxidase Fet3 has been cloned and it has been found to display high sequence similarity to other yeast multicopper oxidases, including all the predicted ligands for the catalytic copper atoms and for the iron substrate. P. pastoris appears to possess a high-affinity iron uptake system similar to that of S. cerevisiae, as far as regulation of expression is concerned. However, the P. pastoris high-affinity iron uptake system presents a K(m) value for iron almost ten times higher than that of S. cerevisiae, possibly to control iron fluxes over a wider range of concentrations of this metal, in order to avoid toxic iron overloading.
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Dipartimento di Scienze Biochimiche A. Rossi Fanelli, Università degli Studi di Roma La Sapienza, P. le A. Moro 5, 00185 Roma, Italy.
Miele
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Maugliani
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Borro
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Bonaccorsi di Patti
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D000595:Amino Acid Sequence; D001483:Base Sequence; D001693:Biological Transport, Active; D002570:Ceruloplasmin / Q000235:genetics* / Q000378:metabolism*; D003001:Cloning, Molecular; D017931:DNA Primers / Q000235:genetics; D015870:Gene Expression; D005800:Genes, Fungal; D007501:Iron / Q000378:metabolism*; D007700:Kinetics; D008969:Molecular Sequence Data; D010843:Pichia / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity
D017931:DNA Primers; D029701:Saccharomyces cerevisiae Proteins; D007501:Iron; D002570:Ceruloplasmin; C085513:FET3 protein, S cerevisiae