Journal
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Volume 106, Issue 38, Pages 16263-16268Publisher
NATL ACAD SCIENCES
DOI: 10.1073/pnas.0904519106
Keywords
Abcb transporters; erythropoiesis; iron and heme metabolism; solute carriers; protein complexes
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Funding
- March of Dimes Foundation
- National Institutes of Health [R01 DK052380, R01 DK070838, P01 HL032262]
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Mitoferrin-1 (Mfrn1; Slc25a37), a member of the solute carrier family localized in the mitochondrial inner membrane, functions as an essential iron importer for the synthesis of mitochondrial heme and iron-sulfur clusters in erythroblasts. The biochemistry of Mfrn1-mediated iron transport into the mitochondria, however, is poorly understood. Here, we used the strategy of in vivo epitope-tagging affinity purification and mass spectrometry to investigate Mfrn1-mediated mitochondrial iron homeostasis. Abcb10, a mitochondrial inner membrane ATP-binding cassette transporter highly induced during erythroid maturation in hematopoietic tissues, was found as one key protein that physically interacts with Mfrn1 during mouse erythroleukemia (MEL) cell differentiation. Mfrn1 was shown previously to have a longer protein half-life in differentiated MEL cells compared with undifferentiated cells. In this study, Abcb10 was found to enhance the stabilization of Mfrn1 protein in MEL cells and transfected heterologous COS7 cells. In undifferentiated MEL cells, cotransfected Abcb10 specifically interacts with Mfrn1 to enhance its protein stability and promote Mfrn1-dependent mitochondrial iron importation. The structural stabilization of the Mfrn1-Abcb10 complex demonstrates a previously uncharacterized function for Abcb10 in mitochondria. Furthermore, the binding domain of Mfrn1-Abcb10 interaction maps to the N terminus of Mfrn1. These results suggest the tight regulation of mitochondrial iron acquisition and heme synthesis in erythroblasts is mediated by both transcriptional and posttranslational mechanisms, whereby the high level of Mfrn1 is stabilized by oligomeric protein complexes.
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