Characterization of two homologous yeast genes that encode mitochondrial iron transporters.
Two different yeast genes were identified that when overexpressed suppressed the low iron growth defect of a mutation in the endoplasmic reticulum iron binding enzyme methyl sterol oxidase. These genes were determined to be novel and highly related. The deduced amino acid sequences indicated that both were membrane proteins having two identical histidine-rich motifs. The predicted proteins, while not ABC transporters, are homologous to a widely distributed family of transition metal transporters present in all kingdoms. Subcellular fractionation and fluorescence microscopy localized these gene products to mitochondria. Based on this result we term these genes Mitochondrial Fe Transporters (MFT). Cells with disruptions in both genes show a growth defect on low iron medium, suggesting that these genes have redundant function and can affect cytosolic iron levels. Measurement of mitochondrial iron in cells grown in iron-rich medium overexpressing MFT1 or MFT2 show a 2-5-fold increase in iron compared with mitochondria from control cells. These results suggest that the mitochondria may act as a reservoir for iron that can be mobilized and used for cytosolic purposes.
Li
L
L
Division of Cell Biology and Immunology, Department of Pathology, University of Utah School of Medicine, Salt Lake City, Utah 84132, USA.
Kaplan
J
J
D000595:Amino Acid Sequence; D001692:Biological Transport; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics*; D027682:Cation Transport Proteins; D019084:Fluorescent Antibody Technique, Indirect; D005800:Genes, Fungal; D049452:Green Fluorescent Proteins; D007501:Iron / Q000378:metabolism; D008164:Luminescent Proteins / Q000032:analysis; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism*; D024101:Mitochondrial Proteins; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid
D002352:Carrier Proteins; D027682:Cation Transport Proteins; D008164:Luminescent Proteins; C109160:MMT1 protein, S cerevisiae; C109161:MMT2 protein, S cerevisiae; D024101:Mitochondrial Proteins; D029701:Saccharomyces cerevisiae Proteins; D049452:Green Fluorescent Proteins; D007501:Iron