Yeast SMF1 Mediates H+-coupled Iron Uptake with Concomitant Uncoupled Cation Currents

Chen, Xing-Zhen; Peng, Ji‐Bin; Cohen, Aviv; Nelson, Hannah; Nelson, Nathan; Hediger, Matthias A.

doi:10.1074/jbc.274.49.35089

Cited by 142 publications

(133 citation statements)

References 37 publications

Supporting

Mentioning

126

Contrasting

Order By: Relevance

“…Expression of Smf1p in Xenopus oocytes demonstrated that this protein mediates H ϩ -dependent divalent metal ion transport (14). In addition, a large Na ϩ leak through Smf1p was observed, and sodium competed with the activity of metal ion uptake.…”

mentioning

confidence: 89%

“…Previously we reported that Na ϩ inhibits metal ion transport by Smf1p and prevents growth of the wild type or ⌬SMF2 strains in the present of EGTA (14). Addition of sodium to the manganese uptake system as described in Fig.…”

Section: Figmentioning

confidence: 99%

“…SMF1 was originally cloned as a high copy number suppressor of a temperaturesensitive mif1-1 mutant (11). Later it was shown that the growth arrest at 37°C could be relieved by supplementing the media with Mn 2ϩ or overexpressing SMF1 that transports Mn 2ϩ from the medium and elevates its concentration in the cytoplasm (8,12,13 (9,12,14). Yeast cells contain additional two genes of this family, SMF2 and SMF3, and indirect evidence indicates that they are also broad range metal ion transporters but exhibit different specificity from SMF1 (10), suggesting a specific function for each of them.…”

mentioning

confidence: 99%

See 2 more Smart Citations

The Family of SMF Metal Ion Transporters in Yeast Cells

Cohen

Nelson

2000

Journal of Biological Chemistry

Self Cite

132

113

View full text Add to dashboard Cite

Metal ions are vital for all organisms, and metal ion transporters play a crucial role in maintaining their homeostasis. The yeast (Saccharomyces cerevisiae) Smf transporters and their homologs in other organisms have a central role in the accumulation of metal ions and their distribution in different tissues and cellular organelles. In this work we generated null mutations in each individual SMF gene in yeast as well as in all combinations of the genes. Each null mutation exhibited sensitivity to metal ion chelators at different concentrations. The combination of null mutants ⌬SMF1 ؉ ⌬SMF2 and the triple null mutant ⌬3SMF failed to grow on medium buffered at pH 8 and 7.5, respectively. Addition of 5 M copper or 25 M manganese alleviated the growth arrest at the high pH or in the presence of the chelating agent. The transport of manganese was analyzed in the triple null mutant and in this mutant expressing each Smf protein. Although overexpression of Smf1p and Smf2p resulted in uptake that was higher than wild type cells, the expression of Smf3p gave no significant uptake above that of the triple mutant ⌬3SMF. Western analysis with antibody against Smf3p indicated that this transporter does not reach the plasma membrane and may function at the Golgi or post-Golgi complexes. The iron uptake resulting from expression of Smf1p and Smf2p was analyzed in a mutant in which its iron transporters FET3 and FET4 were inactivated. Overexpression of Smf1p gave rise to a significant iron uptake that was sensitive to the sodium concentrations in the medium. We conclude that the Smf proteins play a major role in copper and manganese homeostasis and, under certain circumstances, Smf1p may function in iron transport into the cells.Transition metals are essential for many metabolic processes, and their homeostasis is crucial for life processes. Metal ion transporters play a major role in maintaining the correct concentrations of the various metal ions in the different cellular compartments. Recent studies of yeast (Saccharomyces cerevisiae) mutants revealed key elements in metal ion homeostasis, including novel transport systems. Several of the proteins discovered in yeast are highly conserved, and defects in some of the yeast mutants could be complemented by their human homologs (1-4). Some yeast and human homologous proteins were found to be related to copper and iron transport (5-7), among which the most ubiquitous are the SMF family of genes encoding metal ion transporters (8 -10). SMF1 was originally cloned as a high copy number suppressor of a temperaturesensitive mif1-1 mutant (11). Later it was shown that the growth arrest at 37°C could be relieved by supplementing the media with Mn 2ϩ or overexpressing SMF1 that transports Mn 2ϩ from the medium and elevates its concentration in the cytoplasm (8,12,13 (9,12,14). Yeast cells contain additional two genes of this family, SMF2 and SMF3, and indirect evidence indicates that they are also broad range metal ion transporters but exhibit different specificity from SMF1 (10), sugge...

show abstract

mentioning

confidence: 89%

Section: Figmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

The Family of SMF Metal Ion Transporters in Yeast Cells

Cohen

Nelson

2000

Journal of Biological Chemistry

Self Cite

132

113

View full text Add to dashboard Cite

show abstract

“…These constructs were expressed in the yeast smf1 mutant, deficient in a broad range metal transporter nramp homolog (40,41). To test for functional complementation, smf1 mutants transformed with pYES2 containing either Lenramp1, Lenramp3, or empty control vector and, as positive control, wild type yeast were spotted in different dilutions on minimal medium in the presence of 5, 10, 20, and 50 mM divalent metal chelator EGTA.…”

Section: Identification Of Nramp Metal Transportermentioning

confidence: 99%

Differential Regulation of nramp and irt Metal Transporter Genes in Wild Type and Iron Uptake Mutants of Tomato

Bereczky

Wang

Schubert

et al. 2003

Journal of Biological Chemistry

183

149

View full text Add to dashboard Cite

Metal transporters regulated by iron can transport a variety of divalent metals, suggesting that iron regulation is important for specificity of iron transport. In plants, the iron-regulated broad-range metal transporter IRT1 is required for uptake of iron into the root epidermis. Functions of other iron-regulated plant metal transporters are not yet established. To deduce novel plant iron transport functions we studied the regulation of four tomato metal transporter genes belonging to the nramp and irt families with respect to environmental and genetic factors influencing iron uptake. We isolated Lenramp1 and Lenramp3 from tomato and demonstrate that these genes encode functional NRAMP metal transporters in yeast, where they were iron-regulated and localized mainly to intracellular vesicles. Lenramp1 and Leirt1 revealed both root-specific expression and up-regulation by iron deficiency, respectively, in contrast to Leirt2 and Lenramp3. Lenramp1 and Leirt1, but not Lenramp3 and Leirt2, were down-regulated in the roots of fer mutant plants deficient in a bHLH gene regulating iron uptake. In chloronerva mutant plants lacking the functional enzyme for synthesis of the plant-specific metal chelator nicotianamine Leirt1 and Lenramp1 were up-regulated despite sufficient iron supply independent of a functional fer gene. Lenramp1 was expressed in the vascular root parenchyma in a similar cellular pattern as the fer gene. However, the fer gene was not sufficient for inducing Lenramp1 and Leirt1 when ectopically expressed. Based on our results, we suggest a novel function for NRAMP1 in mobilizing iron in the vascular parenchyma upon iron deficiency in plants. We discuss fer/nicotianamine synthase-dependent and -independent regulatory pathways for metal transporter gene regulation.

show abstract

“…Notably, DMT1, identified as an intestinal iron transporter, as well as DMT1 family members in other species (eg, SMF1 in yeast), can transport iron, manganese, zinc, cobalt, and copper. 39,40 The Fet4 transporter in yeast, 41 IRT1 in plants, 42 as well as ZIP14 in mammals 43 transports other transition metals in addition to iron.A recent study has shown that Fpn can transport manganese, suggesting that Fpn may accept other metals as substrates. 44 Our data show that Fpn has modest zinc transport activity.…”

mentioning

confidence: 99%

Induction of FPN1 transcription by MTF-1 reveals a role for ferroportin in transition metal efflux

Troadec¹,

Ward²,

Lo³

et al. 2010

Blood

120

View full text Add to dashboard Cite

IntroductionFerroportin (Fpn) is the only known mammalian iron exporter and plays an essential role in the entry of iron into plasma (for review, see Wessling-Resnick 1 and Wrighting and Andrews 2 ). Fpn is most highly expressed in cells that play a major role in iron acquisition: duodenal enterocytes, macrophages, hepatocytes and syncytial trophoblasts. Fpn, however, can be expressed on a wide variety of other cell types in response to heme 3,4 or iron. [5][6][7] Iron can regulate Fpn expression through transcriptional and translational mechanisms. Ferroportin1 (FPN1), the gene that encodes Fpn, contains a 5Ј iron-responsive element (IRE), which places its translation under the control of iron regulatory proteins. It is thought that the increased expression of Fpn by iron is a response to cellular iron load, as increased cytosolic iron would lead to increased iron export.FPN1 mRNA levels are also increased when cells are exposed to transition metals such as zinc, manganese, cadmium, copper, and other transition metals. 6 In both J774 cells and Caco cells, the increase in Fpn expression resulted in increased iron export. What is unclear, however, is the physiologic function of transition metal-induced expression of Fpn. Iron export in response to increased transition metals may protect cells from transition metal toxicity, perhaps by reducing the potential for iron-induced Fenton chemistry. Alternatively, Fpn might export other metals in addition to iron and thus increased expression of Fpn would directly protect cells from metal toxicity.In this study, we identify at least 1 mechanism by which transition metals induce Fpn expression. We show that zinc and cadmium can activate FPN1 transcription through the Metal Transcription Factor-1 (MTF-1). We also demonstrate that Fpn transports zinc and can protect cells from zinc toxicity. MethodsVector pcDNA3.1-mouse-MTF1-Flag was a gift from Dr G. K. Andrews. 8 We produced a chimera pcDNA3.1-mouse/human-MTF1-Flag by switching the mouse fragment with the human corresponding fragment between KpnI/FseI sites of mouse MTF1-Flag. To express an shRNA against mouse MTF-1, we inserted a double strand oligonucleotide targeting the gtacttcgccaccgctgta sequence of mouse MTF-1 into BamHI and EcoRI sites of pSIREN-DNR-DSRed (Clontech) according to manufacturer's instructions. The mouse/human chimera MTF-1 is resistant to shRNA against mouse MTF-1. The pGL3-control vector (Promega) was modified to perform the luciferase assay. The SV40 promoter was removed by HindIII/NheI digestion and the mouse Fpn promoter (starting at Ϫ2378, Ϫ1154, and Ϫ623 from the TATAA box) was amplified by polymerase chain reaction (PCR) and inserted using same restriction sites. The 5ЈIRE in the FPN1 promoter was deleted by BamHI/SamI digestion as described. 9 The putative metal-responsive elements (MREs) in the Fpn promoter in pGL3 were mutagenized by PCR to produce TCCAGCA*GA*AT*CT*CG and TGGAAGAA*TT*CG*AG (the consensus sequence is underlined, *mutagenized base). Fpn-green fluorescent protein (GFP) was car...

show abstract

Yeast SMF1 Mediates H+-coupled Iron Uptake with Concomitant Uncoupled Cation Currents

Cited by 142 publications

References 37 publications

The Family of SMF Metal Ion Transporters in Yeast Cells

The Family of SMF Metal Ion Transporters in Yeast Cells

Differential Regulation of nramp and irt Metal Transporter Genes in Wild Type and Iron Uptake Mutants of Tomato

Induction of FPN1 transcription by MTF-1 reveals a role for ferroportin in transition metal efflux

Contact Info

Product

Resources

About