A conserved mitochondrial ATP-binding cassette transporter exports glutathione polysulfide for cytosolic metal cofactor assembly

Theresia A Schaedler, Jeremy D Thornton, Inga Kruse, Markus Schwarzländer, Andreas J Meyer, Hendrik W van Veen, Janneke Balk

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Abstract

An ATP-binding cassette (ABC) transporter located in the inner mitochondrial membrane is involved in iron-sulfur cluster and molybdenum cofactor assembly in the cytosol, but the transported substrate is unknown. ATM3 (ABCB25) from Arabidopsis thaliana and its functional orthologue Atm1 from Saccharomyces cerevisiae were expressed in Lactococcus lactis, and studied in inside-out membrane vesicles and in purified form. Both proteins selectively transported glutathione disulfide (GSSG) but not reduced glutathione (GSH) in agreement with a 3-fold stimulation of ATPase activity by GSSG. By contrast, Fe2+ alone or in combination with glutathione did not stimulate ATPase activity. Arabidopsis atm3 mutants were hypersensitive to an inhibitor of glutathione biosynthesis, and accumulated GSSG in the mitochondria. The growth phenotype of atm3-1 was strongly enhanced by depletion of the mitochondria-localized, GSH-dependent persulfide oxygenase ETHE1, suggesting that the physiological substrate of ATM3 contains persulfide in addition to glutathione. Consistent with this idea, a transportomics approach using mass spectrometry showed that glutathione trisulfide (GS-S-SG) was transported by Atm1. We propose that mitochondria export glutathione polysulfide, containing glutathione and persulfide, for iron-sulfur cluster assembly in the cytosol.
Original languageEnglish
Pages (from-to)23264-23274
Number of pages11
JournalJournal of Biological Chemistry
Volume289
Early online date8 Jul 2014
DOIs
Publication statusPublished - 22 Aug 2014

Keywords

  • ABC transporter
  • Arabidopsis
  • iron-sulfur protein
  • mitochondria
  • yeast
  • glutathione
  • transportomics

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