Evidence for mitochondrial localization of divalent metal transporter 1 (DMT1).
In mammalian cells, mitochondria receive most incoming iron, yet no entry pathway for iron at the outer mitochondrial membrane (OMM) has been characterized. Our results show that the divalent metal transporter 1 (DMT1) occurs in the OMM. Immunoblots detected DMT1 in mitochondria from a pneumocyte cell model in their OMM. Using the split-ubiquitin yeast 2-hybrid system, we found that cytochrome c oxidase subunit II (COXII) and the translocase of OMM 6-kDa subunit (Tom6) homologue interact with DMT1. COXII coimmunoprecipitates with DMT1. There are 4 DMT1 isoforms that differ at the N and C termini. Using HEK293 cells that inducibly express all of the 4 ends of DMT1, we found all of them in the OMM, as detected by immunoblots after cell fractionation, and in isolated mitochondria, as detected by immunofluorescence. Immunoblot analysis of purified cell fractions from rat renal cortex confirmed and extended these results to the kidney, which expressed high levels of DMT1. Immunogold labeling detected DMT1 colocalization in mitochondria with the voltage-dependent anion-selective channel protein-1, which is expressed in the OMM. We suggest that DMT1 not only exports iron from endosomes, but also serves to import the metal into the mitochondria.
1Department of Physiology and Pathophysiology and ZBAF, University of Witten/Herdecke, Stockumer Strasse 12, D-58453 Witten, Germany. F.T., frank.thevenod@uni-wh.de.
Natascha A
NA
Wolff
Andrew J
AJ
Ghio
Laura M
LM
Garrick
Michael D
MD
Garrick
Lin
L
Zhao
Robert A
RA
Fenton
Frank
F
Thévenod
D056809:Alveolar Epithelial Cells / Q000166:cytology; D000818:Animals; D000838:Anions; D027682:Cation Transport Proteins / Q000378:metabolism*; D003576:Electron Transport Complex IV / Q000378:metabolism; D011992:Endosomes / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D007672:Kidney Cortex / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism*; D033681:Mitochondrial Membrane Transport Proteins / Q000378:metabolism; D051336:Mitochondrial Membranes / Q000378:metabolism*; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D010957:Plasmids / Q000378:metabolism; D020033:Protein Isoforms / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D000099236:Solute Carrier Family 11, Member 2
D000838:Anions; D027682:Cation Transport Proteins; D003576:Electron Transport Complex IV; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D020033:Protein Isoforms; D029701:Saccharomyces cerevisiae Proteins; D000099236:Solute Carrier Family 11, Member 2; C082532:TOM6 protein, S cerevisiae; C117108:cytochrome C oxidase subunit II
adenine nucleotide translocator; early endosomal antigen 1; kiss-and-run; lysosome-associated membrane protein; transferrin