A conserved mitochondrial ATP-binding cassette transporter exports glutathione polysulfide for cytosolic metal cofactor assembly.
A conserved mitochondrial ATP-binding cassette transporter exports glutathione polysulfide for cytosolic metal cofactor assembly.
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DOI：
10.1074/jbc.m114.553438
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发表时间：
2014-08-22
期刊：
影响因子：
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通讯作者：
Balk J
中科院分区：
文献类型：
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作者：
Schaedler TA;Thornton JD;Kruse I;Schwarzländer M;Meyer AJ;van Veen HW;Balk J
背景：线粒体 ABC 转运蛋白 (ATM) 是细胞质铁硫簇和钼辅因子形成所必需的。结果：拟南芥 ATM3 和酵母 Atm1 转运放射性标记的谷胱甘肽二硫化物 (GSSG)。通过质谱分析证明了谷胱甘肽三硫化物 (GS-S-SG) 的转运。结论：线粒体转运蛋白输出谷胱甘肽多硫化物。意义：ATM 底物的鉴定定义了它们在金属辅因子组装和铁稳态中的作用。位于线粒体内膜的 ATP 结合盒转运蛋白参与细胞质中铁硫簇和钼辅因子的组装，但转运的底物未知。来自拟南芥的 ATM3 (ABCB25) 及其来自酿酒酵母的功能性同源物 Atm1 在乳酸乳球菌中表达，并以纯化形式在内外膜囊泡中进行研究。两种蛋白都选择性转运谷胱甘肽二硫化物 (GSSG)，但不还原谷胱甘肽，这与 GSSG 对 ATP 酶活性的 3 倍刺激一致。相比之下，单独使用 Fe2+ 或与谷胱甘肽组合使用不会刺激 ATP 酶活性。拟南芥 atm3 突变体对谷胱甘肽生物合成抑制剂高度敏感，并在线粒体中积累 GSSG。 atm3-1 的生长表型因线粒体定位、GSH 依赖性过硫化物加氧酶 ETHE1 的消耗而强烈增强，这表明 ATM3 的生理底物除了谷胱甘肽外还含有过硫化物。与这个想法一致，使用质谱的运输组学方法表明，谷胱甘肽三硫化物 (GS-S-SG) 由 Atm1 运输。我们认为线粒体输出谷胱甘肽多硫化物，含有谷胱甘肽和过硫化物，用于细胞质中的铁硫簇组装。
Background: ABC transporters of mitochondria (ATM) are required for formation of cytosolic iron-sulfur clusters and molybdenum cofactor. Results: Arabidopsis ATM3 and yeast Atm1 transport radiolabeled glutathione disulfide (GSSG). Transport of glutathione trisulfide (GS-S-SG) was demonstrated by mass spectrometry. Conclusion: A mitochondrial transporter exports glutathione polysulfide. Significance: Identification of substrate(s) of ATMs defines their role in metal cofactor assembly and iron homeostasis. An ATP-binding cassette 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 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 mitochondrion-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.