A permease-oxidase complex involved in high-affinity iron uptake in yeast

Science

Volumn 271, Issue 5255, 1996, Pages 1552-1557

  Stearman, Robert ^a   Yuan, Daniel S ^a   Yamaguchi Iwai, Yuko ^a   Klausner, Richard D ^a   Dancis, Andrew ^a  

^a EUNICE KENNEDY SHRIVER NATIONAL INSTITUTE OF CHILD HEALTH AND HUMAN DEVELOPMENT   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

COPPER; IRON; MEMBRANE ENZYME; OXIDOREDUCTASE; PERMEASE;

ARTICLE; CELL MEMBRANE TRANSPORT; CONTROLLED STUDY; ENZYME ACTIVITY; GENE EXPRESSION; GENE MUTATION; IRON TRANSPORT; NONHUMAN; PRIORITY JOURNAL; PROTEIN TRANSPORT; YEAST;

AMINO ACID SEQUENCE; BINDING SITES; BIOLOGICAL TRANSPORT; CARRIER PROTEINS; CELL MEMBRANE; CERULOPLASMIN; COPPER; ENDOPLASMIC RETICULUM; FERRIC COMPOUNDS; FERRITINS; FERROUS COMPOUNDS; GENES, FUNGAL; GOLGI APPARATUS; IRON; MEMBRANE TRANSPORT PROTEINS; MODELS, BIOLOGICAL; MOLECULAR SEQUENCE DATA; MULTIENZYME COMPLEXES; MUTATION; OPEN READING FRAMES; OXIDATION-REDUCTION; OXIDOREDUCTASES; SACCHAROMYCES CEREVISIAE; SACCHAROMYCES CEREVISIAE PROTEINS; TRANSFORMATION, GENETIC;

EID: 0029921680     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.271.5255.1552     Document Type: Article

References (72)

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16. R. J. P. Williams, in (1), pp. 2-15.
17. The transport of iron charactenzed here must be distinguished from the transport of iron-siderophore complexes that occurs in most bacteria. Bacteria secrete high-affinity ferric iron chelators called siderophores (43), and iron transport is achieved by uptake of the fernsiderophore complex (43). Most eukaryotes, including S. cerevisiae, do not synthesize siderophores (44).
18. Genetic studies in E coll have led to identification of the feo gene as a candidate iron transporter, functioning in the absence of siderophores under anaerobic growth conditions [M. Kammler, C. Schon, K Hantke, J. Bacteriol. 175, 6212 (1993)]. In S. cerevislae, iron uptake requires the sequential action of extemally directed ferne reductases (encoded by the FRE1 and FRE2 genes), and a high-affinity ferrous iron transport system (subject of this paper) or a low-affinity ferrous transport system encoded by FET4 [D R Dix. J T. Bridgham, M. A Broderius, C. A. Byersdorfer, D Eide, J Biol. Chem. 269, 26092 (1994)]. Homologs of FET4 or feo have not been identified in other species. In humans, candidate iron transporters have been identified through isolation of iron-binding proteins from human intestine [M. E. Conrad et al, Blood 81, 517 (1993)] and through in vitro studies of the proton-pumping ATPase of erythrocytes [C Li, J. A Watkins, J. Glass, J. Biol. Chem. 269, 10242 (1994] For a review of human iron metabolism, see G. M. Brittenham, in Hematology. Basic Principles and Practice, R. Huffman et al., Eds. (Churchill Livingstone, New York, 1995), pp 492-523. The human genetic disease hemochromatosis, characterized by unregulated iron accumulation and consequent organ damage, has been described by T. H. Bothwell, R. W. Chartton, and A G. Motulsky [in The Metabolic and Molecular Bases of Inherited Disease, C. R Scriver, A L Beaudet, W S. Sly, D. Valle. Eds (McGraw-Hill, New York, 1995), pp 2237-2269]. The gene for this disease has not been cloned.
19. Genetic studies in E coll have led to identification of the feo gene as a candidate iron transporter, functioning in the absence of siderophores under anaerobic growth conditions [M. Kammler, C. Schon, K Hantke, J. Bacteriol. 175, 6212 (1993)]. In S. cerevislae, iron uptake requires the sequential action of extemally directed ferne reductases (encoded by the FRE1 and FRE2 genes), and a high-affinity ferrous iron transport system (subject of this paper) or a low-affinity ferrous transport system encoded by FET4 [D R Dix. J T. Bridgham, M. A Broderius, C. A. Byersdorfer, D Eide, J Biol. Chem. 269, 26092 (1994)]. Homologs of FET4 or feo have not been identified in other species. In humans, candidate iron transporters have been identified through isolation of iron-binding proteins from human intestine [M. E. Conrad et al, Blood 81, 517 (1993)] and through in vitro studies of the proton-pumping ATPase of erythrocytes [C Li, J. A Watkins, J. Glass, J. Biol. Chem. 269, 10242 (1994] For a review of human iron metabolism, see G. M. Brittenham, in Hematology. Basic Principles and Practice, R. Huffman et al., Eds. (Churchill Livingstone, New York, 1995), pp 492-523. The human genetic disease hemochromatosis, characterized by unregulated iron accumulation and consequent organ damage, has been described by T. H. Bothwell, R. W. Chartton, and A G. Motulsky [in The Metabolic and Molecular Bases of Inherited Disease, C. R Scriver, A L Beaudet, W S. Sly, D. Valle. Eds (McGraw-Hill, New York, 1995), pp 2237-2269]. The gene for this disease has not been cloned.
20. Genetic studies in E coll have led to identification of the feo gene as a candidate iron transporter, functioning in the absence of siderophores under anaerobic growth conditions [M. Kammler, C. Schon, K Hantke, J. Bacteriol. 175, 6212 (1993)]. In S. cerevislae, iron uptake requires the sequential action of extemally directed ferne reductases (encoded by the FRE1 and FRE2 genes), and a high-affinity ferrous iron transport system (subject of this paper) or a low-affinity ferrous transport system encoded by FET4 [D R Dix. J T. Bridgham, M. A Broderius, C. A. Byersdorfer, D Eide, J Biol. Chem. 269, 26092 (1994)]. Homologs of FET4 or feo have not been identified in other species. In humans, candidate iron transporters have been identified through isolation of iron-binding proteins from human intestine [M. E. Conrad et al, Blood 81, 517 (1993)] and through in vitro studies of the proton-pumping ATPase of erythrocytes [C Li, J. A Watkins, J. Glass, J. Biol. Chem. 269, 10242 (1994] For a review of human iron metabolism, see G. M. Brittenham, in Hematology. Basic Principles and Practice, R. Huffman et al., Eds. (Churchill Livingstone, New York, 1995), pp 492-523. The human genetic disease hemochromatosis, characterized by unregulated iron accumulation and consequent organ damage, has been described by T. H. Bothwell, R. W. Chartton, and A G. Motulsky [in The Metabolic and Molecular Bases of Inherited Disease, C. R Scriver, A L Beaudet, W S. Sly, D. Valle. Eds (McGraw-Hill, New York, 1995), pp 2237-2269]. The gene for this disease has not been cloned.
21. Genetic studies in E coll have led to identification of the feo gene as a candidate iron transporter, functioning in the absence of siderophores under anaerobic growth conditions [M. Kammler, C. Schon, K Hantke, J. Bacteriol. 175, 6212 (1993)]. In S. cerevislae, iron uptake requires the sequential action of extemally directed ferne reductases (encoded by the FRE1 and FRE2 genes), and a high-affinity ferrous iron transport system (subject of this paper) or a low-affinity ferrous transport system encoded by FET4 [D R Dix. J T. Bridgham, M. A Broderius, C. A. Byersdorfer, D Eide, J Biol. Chem. 269, 26092 (1994)]. Homologs of FET4 or feo have not been identified in other species. In humans, candidate iron transporters have been identified through isolation of iron-binding proteins from human intestine [M. E. Conrad et al, Blood 81, 517 (1993)] and through in vitro studies of the proton-pumping ATPase of erythrocytes [C Li, J. A Watkins, J. Glass, J. Biol. Chem. 269, 10242 (1994] For a review of human iron metabolism, see G. M. Brittenham, in Hematology. Basic Principles and Practice, R. Huffman et al., Eds. (Churchill Livingstone, New York, 1995), pp 492-523. The human genetic disease hemochromatosis, characterized by unregulated iron accumulation and consequent organ damage, has been described by T. H. Bothwell, R. W. Chartton, and A G. Motulsky [in The Metabolic and Molecular Bases of Inherited Disease, C. R Scriver, A L Beaudet, W S. Sly, D. Valle. Eds (McGraw-Hill, New York, 1995), pp 2237-2269]. The gene for this disease has not been cloned.
22. Genetic studies in E coll have led to identification of the feo gene as a candidate iron transporter, functioning in the absence of siderophores under anaerobic growth conditions [M. Kammler, C. Schon, K Hantke, J. Bacteriol. 175, 6212 (1993)]. In S. cerevislae, iron uptake requires the sequential action of extemally directed ferne reductases (encoded by the FRE1 and FRE2 genes), and a high-affinity ferrous iron transport system (subject of this paper) or a low-affinity ferrous transport system encoded by FET4 [D R Dix. J T. Bridgham, M. A Broderius, C. A. Byersdorfer, D Eide, J Biol. Chem. 269, 26092 (1994)]. Homologs of FET4 or feo have not been identified in other species. In humans, candidate iron transporters have been identified through isolation of iron-binding proteins from human intestine [M. E. Conrad et al, Blood 81, 517 (1993)] and through in vitro studies of the proton-pumping ATPase of erythrocytes [C Li, J. A Watkins, J. Glass, J. Biol. Chem. 269, 10242 (1994] For a review of human iron metabolism, see G. M. Brittenham, in Hematology. Basic Principles and Practice, R. Huffman et al., Eds. (Churchill Livingstone, New York, 1995), pp 492-523. The human genetic disease hemochromatosis, characterized by unregulated iron accumulation and consequent organ damage, has been described by T. H. Bothwell, R. W. Chartton, and A G. Motulsky [in The Metabolic and Molecular Bases of Inherited Disease, C. R Scriver, A L Beaudet, W S. Sly, D. Valle. Eds (McGraw-Hill, New York, 1995), pp 2237-2269]. The gene for this disease has not been cloned.
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38. UP) (19), Y18 (aft1::TRP1) (19) Strains derived from the related strain 81 (MATa gcn4-101 his3-609 Ieu2-3, 112 ino1-13 ura3-52 FRE1-HIS3..URA3). TR4 (ftr1-2), 2C (fet3-2C). Mutations at the MA15 locus, for which the gene has not been cloned, resuit in high iron uptake TR1p was created by patching TR1 onto 5-fluoroorotic acid plates to eject the FRE1-HIS3 construct and recover the uracil auxotrophy. DEY1397-6A (MATα ura3-52 leu2-3, 112 trp1-1 his3-11,15 ade2-1 can1-100 fet3.-HIS3) (11) was used in several crosses. Strains with a different genetic background were derived from the parental strain YPH252 (MATα ura3-52 Iys2-801 ade2-101 trp1-Δ1 his3-Δ200 leu2-Δ7): YPHfa (Δfet3.:TRP1) (12). The parental strain of the opposite mating type, YPH250, was used to construct a deletion of FTR1, strain 42C (ftr1Δ1::TRP1).
39. Mutant selection: Strain 61 was grown on agar plates made from modified SD medium lacking histidine and including 100 μM ferric ammonium sul fate, 10 μM copper sulfate, and 50 mM MES buffer (pH 6.1). Strains E10 (ma15-3 ftr1-1), E31 (ma15-4 ftr1-2), and E30 (ma15-2 fet3-2C) were derived from colonies that appeared on these plates after 8 days. They were evaluated and found to be deficient in iron uptake. Diploids formed by crossing these strains with strain 81 exhibited normal iron uptake activity. The E10×81diploid was then sporulated, and spore clones were sorted into three categones: (i) Single mutants lacking iron uptake (ftr1-1); (ii) single mutants with high iron uptake (ma 15-3); and (iii) double mutants lacking iron uptake (ma15-3 ftr1-1). The double mutants could be identified, because backcrossing to the parental strains 81 or 61 and sporulation resulted in segregation of the high iron uptake and low iron uptake traits in the spore clones. Strain TR1 (ffr1-1) was denved from a spore clone lacking iron uptake activity and with a single mutation. In a similar manner, the E31×81 diploid was sporulated, and spore clone TR4 (ftr1-2) was identified. The diploid strain, E30×81, was sporulated, and spore clone 2C (fet3-2C) was identified 2C (fet3-2C) was found to contain a mutant allele of FET3, because a diploid formed by crossing with DEY1397-6A (fet3::HIS3) lacked iron uptake activity. TR1 (ftr1-1) and TR4 (ftr1-2) were found to contain mutant alleles of the same gene, because the dipfoid formed by crossing TR1 with TR4 lacked iron uptake activity. Mating of TR4 with strains 64 (Δctr1::LEU2), DEY1397-6A (tet3::HIS3), or YRS3 (ccc2::URA3) yielded diploids, each with normal iron uptake activity.
40. Strains 61 (parental), 2C (fet3-2C), and TR1 (ftr1-1) were spread onto agar plates containing YPD (2% yeast extract, 1% peptone, and 2% glucose), or SD modified to contain sufficient iron or limited iron. Formulation of the modrfed SD plates (per liter): 6.7 g yeast nitrogen base without amino acids (Difco), 0.8 g CSM or CSM-ura (Bio101), 20 g glucose, 50 mM MES (pH 6.1) (Sigma), and 1 mM ferrozine (Fluka) The ingredients were dissolved in distilled, deionized water and filter-stenlized through a 0.45-μm nitrocellulose membrane (Nalgene). Ten grams of Bacto-Agar (Difco) were added to the filtrate and dissolved by heating in a microwave oven After cooling to 55°C, a freshly dissolved stocket ferrous ammonium sulfate (10 mM, Fluka) was added to a final concentration of 50 μM (iron-limited plates) or 350 μM (ironsufficient plates). All strains formed colonies of comparable size on the YPD or iron-sufficient plates, but 2C and TR1 formed only micro-colonies on the ironlimited plates.
41. R. L Chaney, J. Plant Nutr 11, 1033 (1988); L. L. Stookey, Anal Chem. 42, 779 (1970).
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43. M. D. Rose, P. Novick, J. H. Thomas, D. Botstein, G R. Fink, Gene 60, 237 (1987).
44. + colony growing on low-iron plates. Using primers flanking the Bam HI site, we sequenced the ends of the yeast DNA insert, and the complementing region was narrowed to the Sna BI-Afl II fragment of 2065 base pairs (bp) [chromosome V, nt 457, 777 to 455, 711] conlaining the ORF YER145C (GenBank accession number U18917). This fragment was subcloned into pUC18 for further manipulations (pUC18/FTR1) Identification of the FTR1 ORF. pUC18/FTR1 was digested with either Eco RV or Bst XI. The Bst XI 3′ overhang was removed with T4 DNA polymerase, and an oligonucleotide was ligated to the blunt ends, introducing stop codons in three frames at the Eco RV or Bst XI sites of the FTRI ORF. The FTRI constructs in pUC18 were then returned to yeast shuttle vectors, creating the following plasmids: 351FTR1 (genomic fragment in high copy number vector with LEU2 marker), 351FTR1tBstXI (same, but with FTR1 coding region truncated at Bst XI site), and 351FTR1tEcoRV (same, but with FTR1 coding region truncated at Eco RV site). The truncated vanants of the FTR1 ORF were unable to complement the iron uptake defect of TR1p (ftr1-1). FET3 plasmid. A 2.8-kb Hind III-Eco RV genomic fragment derived from the clone pDS8 (11) was inserted in plasmid YEp352, creating plasmid 352FET3 (high copy number with URA3 marker).
45. The marked strain 42C(ftr1Δ1:.TRP1) was crossed with TR1(ffr1-1) and sporulated. Tetrads from 24 meioses were evaluated, and all segregants were deficient in iron uptake.
46. The conceptual translation of the FTR1 ORF was analyzed with the TMpred program (45) This same amino acid sequence was then used to query the sequence data base (non-redundant PDB + GBup-date + GenBank + EMBLupdate + EMBL, 14 November 1995) with the BLAST algorithm (46). Similar ORFs identified were as follows: YBR207w (Gen-Bank accession number Z36076) from chromosome II of S. cerevisiae, which we have called FTH1, gave a probability score of 4 0e-84. SPACIF7.07c (accession number Z67998) from S. pombe gave a probability score of 2.2e-105. An adjacent and divergently transcribed ORF in S. pombe, SPAC1 F7.08 (accession number Z67998), was similar to FET3 and gave a probability score of 2.0e-120. ipa-27d (accession number X73124) of B. subtilis gave a probability score of 6.4e-07 when compared with FTR1. The PileUp program (47) was used to align similar amino acid sequences, and BESTFIT (47) was used to determine percent identity between similar proteins.
47. A Bagg and J. B. Nielands, Biochemistry 26, 5471 (1987).
48. Single-letter abbreviations for the amino acid residues are as follows. A, Ala. C, Cys, D, Asp; E, Glu; F, Phe; G, Gly; H, His; I, Ile, K, Lys; L, Leu; M, Met; N, Asn; P, Pro; Q, Gln; R, Arg, S, Ser; T, Thr; V, Val, W, Trp; and Y, Tyr
49. Prosite entries PS00540, PS00204 for femtin metal binding sites; R. R Crichton, in Inorganic Biochemistry of Iron Metabolism (Horwood, New York, 1991), pp 144-154; S. Levi et al, J. Mol Biol. 238, 649 (1994); S. J. Lippard and J. M Berg, Principles of Bioinorganic Chemistry (University Science Books, Mill Valley, CA, 1994), pp. 125-130; J. Trikha, E C. Theil, N M. Allewell, J. Mol. Biol. 248, 949 (1995).
50. Prosite entries PS00540, PS00204 for femtin metal binding sites; R. R Crichton, in Inorganic Biochemistry of Iron Metabolism (Horwood, New York, 1991), pp 144-154; S. Levi et al, J. Mol Biol. 238, 649 (1994); S. J. Lippard and J. M Berg, Principles of Bioinorganic Chemistry (University Science Books, Mill Valley, CA, 1994), pp. 125-130; J. Trikha, E C. Theil, N M. Allewell, J. Mol. Biol. 248, 949 (1995).
51. Prosite entries PS00540, PS00204 for femtin metal binding sites; R. R Crichton, in Inorganic Biochemistry of Iron Metabolism (Horwood, New York, 1991), pp 144-154; S. Levi et al, J. Mol Biol. 238, 649 (1994); S. J. Lippard and J. M Berg, Principles of Bioinorganic Chemistry (University Science Books, Mill Valley, CA, 1994), pp. 125-130; J. Trikha, E C. Theil, N M. Allewell, J. Mol. Biol. 248, 949 (1995).
52. Prosite entries PS00540, PS00204 for femtin metal binding sites; R. R Crichton, in Inorganic Biochemistry of Iron Metabolism (Horwood, New York, 1991), pp 144-154; S. Levi et al, J. Mol Biol. 238, 649 (1994); S. J. Lippard and J. M Berg, Principles of Bioinorganic Chemistry (University Science Books, Mill Valley, CA, 1994), pp. 125-130; J. Trikha, E C. Theil, N M. Allewell, J. Mol. Biol. 248, 949 (1995).
53. up), and Y18 (aft1 interruption) strains (27), each grown in ironreplete or iron-starved media The FTR1 mRNA was induced by iron deprivation and repressed by iron availability in strain 61, but was constitutively present in the M2 strain and virtually undetectable in the Y18 strain (Y. Yamaguchi-Iwai, R. Steamnan, A Danois, R. D. Klausner, in preparation).
54. J. Rine, Methods. Enzymol 194, 239 (1991)
55. Rabbit antibody against FET3 protein (39) was used to evaluate FET3 protein levels by immunoblotting of cell lysates from the wild-type strain YPH252 and the same strain transformed with plasmid 352FET3. The protein was overexpressed roughly fivefold in the transformed strain.
56. Deletion of FTR1 from the genome: For constructing strain 42C (ftr7Δ7::TRP1), 200-bp DNA fragments flanking the FTR1 ORF were generated by PCR. The 5′ fragment contained a unique Acc65 I site, and the 3′ fragment contained a Bgl II site adjacent to the coding region. A third fragment containing the TRP1 gene was generated by PCR with matching restnction sites. These fragments were digested and ligated in vitro, and then PCR with flanking primers was used to amplify the entire construct. The PCR-generated fragment was used to transform YPH250 to prototrophy for tryptophan, and the correctness of the genomic insertion was validated by PCR from the TRP1 marker and flanking DNA sequences in the genome.
57. Mutagenesis of FTR1: Point mutations were introduced into the plasmid 351FTR1 by standard protocols (Chameleon, Stratagene). The REGLE amino acid sequence motif of the FTR1 protein was mutated to RAGLE, REGLA, or RAGLA. creating plasmids 351RAGLE, 351REGLA, and 351RAGLA The presence of the expected mutations was verified by sequencing, and three independently derived mutant clones were used in these expenments. The Sst 1-Eco RV fragment of plasmid 351 REGLA, containing the mutated sequences, was used to replace the corresponding fragment in pUC18-FTR1myc. The entire Sst 1-Sal I fragment was then transferred to the corresponding sites of p702, creating 702RFGLAmyc.
58. Epitope tag insertion: The 10-amino acid MYC tag sequence (EQKLISEEDL) (38) was introduced at the COOH-terminus of the FTR1 protein in two steps. First, the restriction sites, Bgl II and Spe I, were inserted at the COOH-terminus of the FTR1 ORF in plasmid pUC18-FTR1. This was accomplished by PCR to generate a replacement fragment with the additional restriction sites between the genomic Bst XI and Dra III sites. Two amino acids (lysine and serine) were added to the COOH-terminus of the FTR1 protein as a result of introducing the Bgl II site. Next, complementary, synthetic oligonucleotides encoding the MYC tag flanked by Bgl II and Spe I cohesive ends were synthesized. These olrgonucleotides were annealed and ligated into the corresponding restriction sites of the modified pUC18-FTR1 plasmid. The plasmid, pUC18-FTR1myc, was sequenced between the Bst XI and Dra III sites, thereby verifying the presence of the sequences coding for the added COOH-terminal amino acids KSEQKLSEEDL The FT/97 constructs in pUC18 were returned to yeast shuttle vectors, creating the plasmids 351FTR1myc (genomic fragment with MYC tag added at the COOH-terminus of the coding sequence) and 702-FTR1myc (same fragment in a low copy number vector with LEU2 marker). The epitope insertion did not interfere with the ability of the modified FTR1 to complement the iron uptake defect of an ftr1 deletion strain, 42C (21)
59. P. A Kolodziej and R. Young, Methods Enzymol. 194, 508 (1991).
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63. ORF name YFL041w (GenBank accession number P38993).
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67. K. Hofmann and W. Staffel, Biol. Chem. Hoppe-Seyler 347, 166 (1993)
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69. Program Manual forthe Wisconsin Package, Version 8 (Genetics Computer Group, Madison, WI, 1994)
70. C. J. Roberts, C. K. Raymond, C. T. Yamashiro, T. H Stevens, Methods Enzymol 194, 644 (1991)
71. Immunofluorescence: Strains were grown in ironfree medium and fixed in formaldehyde. Treatment for 1 hour with oxylytioase (1 mg/ml; Enzogenetics) was followed by a 2-min treatment with 2% SDS. After removal of SDS, the cells were fixed to polylysine-coated cover slips (48). The cover slips were incubated with 9E10 ascites (1 1000), washed, and incubated with Cy3-conjugated rabbit antibody to mouse immunoglobulin G (Jackson Immunoresearch). In some instances, DAPI (Sigma) was added to slain the nucleus. Cells were visualized with a Zeiss photomicroscope
72. We thank F. S. Dietnch for providing sequence information from the S. cerevisiae genome project before publication; J. Bonifacino, T. Rouault, G. Storz, and J. Stubbe for critical review of the manuscript and helpful conversations and comments; and N. Brun and J. Kelly for assisting with preparation of Fig. 7 s