title: Functional characterization of the ferroxidase, permease high-affinity iron transport complex from Candida albicans.
abstract: Saccharomyces cerevisiae expresses two proteins that together support high-affinity Fe-uptake. These are a multicopper oxidase, Fet3p, with specificity towards Fe²⁺ and a ferric iron permease, Ftr1p, which supports Fe-accumulation. Homologues of the genes encoding these two proteins are found in all fungal genomes including those for the pathogens, Candida albicans and Cryptococcus neoformans. At least one of these loci represents a virulence factor for each pathogen suggesting that this complex would be an appropriate pharmacologic target. However, the mechanism by which this protein pair supports Fe-uptake in any fungal pathogen has not been elucidated. Taking advantage of the robust molecular genetics available in S. cerevisiae, we identify the two of five candidate ferroxidases likely involved in high-affinity Fe-uptake in C. albicans, Fet31 and Fet34. Both localize to the yeast plasma membrane and both support Fe-uptake along with an Ftr1 protein, either from C. albicans or from S. cerevisiae. We express and characterize Fet34, demonstrating that it is functionally homologous to ScFet3p. Using S. cerevisiae as host for the functional expression of the C. albicans Fe-uptake proteins, we demonstrate that they support a mechanism of Fe-trafficking that involves channelling of the CaFet34-generated Fe³⁺ directly to CaFtr1 for transport into the cytoplasm.
authors.affiliation: Department of Biochemistry, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY 14214, USA.
authors.forename: Lynn
authors.initials: L
authors.lastname: Ziegler
authors.forename: Alaina
authors.initials: A
authors.lastname: Terzulli
authors.forename: Ruchi
authors.initials: R
authors.lastname: Gaur
authors.forename: Ryan
authors.initials: R
authors.lastname: McCarthy
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Kosman
mesh_terms: D002176:Candida albicans / Q000201:enzymology* / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry / Q000201:enzymology; D002570:Ceruloplasmin / Q000378:metabolism*; D003455:Cryptococcus neoformans; D005656:Fungal Proteins / Q000378:metabolism*; D007501:Iron / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000378:metabolism*; D008954:Models, Biological; D008958:Models, Molecular; D012441:Saccharomyces cerevisiae
chemical_list: C429223:FTR1 protein, Candida albicans; D005656:Fungal Proteins; D026901:Membrane Transport Proteins; D007501:Iron; D002570:Ceruloplasmin