Yeast Mitochondria Import Aqueous FeII and, When Activated for Iron–Sulfur Cluster Assembly, Export or Release Low-Molecular-Mass Iron and Also Export Iron That Incorporates into Cytosolic Proteins,Journal of the American Chemical Society

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Yeast Mitochondria Import Aqueous FeII and, When Activated for Iron–Sulfur Cluster Assembly, Export or Release Low-Molecular-Mass Iron and Also Export Iron That Incorporates into Cytosolic Proteins
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2023-06-20 , DOI: 10.1021/jacs.2c13439
Rachel E Shepherd ₁ , Alexia C Kreinbrink ₂ , Cybele Lemuh Njimoh ₂ , Shaik Waseem Vali ₂ , Paul A Lindahl _{1,

2}

Affiliation

Iron–sulfur cluster (ISC) assembly occurs in both mitochondria and cytosol. Mitochondria are thought to export a low-molecular-mass (LMM) iron and/or sulfur species which is used as a substrate for cytosolic ISC assembly. This species, called X–S or (Fe–S)_int, has not been directly detected. Here, an assay was developed in which mitochondria were isolated from ⁵⁷Fe-enriched cells and incubated in various buffers. Thereafter, mitochondria were separated from the supernatant, and both fractions were investigated by ICP-MS-detected size exclusion liquid chromatography. Aqueous ⁵⁴Fe^II in the buffer declined upon exposure to intact ⁵⁷Fe-enriched mitochondria. Some ⁵⁴Fe was probably surface-absorbed but some was incorporated into mitochondrial iron-containing proteins when mitochondria were activated for ISC biosynthesis. When activated, mitochondria exported/released two LMM nonproteinaceous iron complexes. One species, which comigrated with an Fe-ATP complex, developed faster than the other Fe species, which also comigrated with phosphorus. Both were enriched in ⁵⁴Fe and ⁵⁷Fe, suggesting that the added ⁵⁴Fe entered a pre-existing pool of ⁵⁷Fe, which was also the source of the exported species. When ⁵⁴Fe-loaded ⁵⁷Fe-enriched mitochondria were mixed with isolated cytosol and activated, multiple cytosolic proteins became enriched with Fe. No incorporation was observed when ⁵⁴Fe was added directly to the cytosol in the absence of mitochondria. This suggests that a different Fe source in mitochondria, the one enriched mainly with ⁵⁷Fe, was used to export a species that was ultimately incorporated into cytosolic proteins. Iron from buffer was imported into mitochondria fastest, followed by mitochondrial ISC assembly, LMM iron export, and cytosolic ISC assembly.

中文翻译：

酵母线粒体输入水性 FeII，当被激活以进行铁硫簇组装时，输出或释放低分子量铁，还输出掺入胞浆蛋白的铁

铁硫簇（ISC）组装发生在线粒体和细胞质中。线粒体被认为输出低分子质量 (LMM) 铁和/或硫物质，用作细胞质 ISC 组装的底物。这种物质称为 X–S 或 (Fe–S) _int，尚未被直接检测到。^{在此，开发了一种测定方法，从57 个}富含 Fe 的细胞中分离线粒体并在各种缓冲液中孵育。此后，从上清液中分离线粒体，并通过 ICP-MS 检测的尺寸排阻液相色谱法对两种级分进行研究。暴露于完整的⁵⁷ Fe 富集线粒体后，缓冲液中的水性⁵⁴ Fe ^II下降。约⁵⁴Fe 可能被表面吸收，但当线粒体被激活进行 ISC 生物合成时，一些 Fe 会被掺入线粒体含铁蛋白中。当激活时，线粒体输出/释放两种 LMM 非蛋白质铁复合物。一种与 Fe-ATP 复合物共迁移的物种比其他也与磷共迁移的 Fe 物种发育得更快。两者都富含⁵⁴ Fe 和⁵⁷ Fe，表明添加的⁵⁴ Fe 进入了预先存在的⁵⁷ Fe 池，这也是出口物种的来源。⁵⁴载铁时⁵⁷富含铁的线粒体与分离的细胞质混合并被激活，多种细胞质蛋白变得富含铁。当在不存在线粒体的情况下将⁵⁴ Fe 直接添加到胞质溶胶中时，没有观察到掺入。这表明线粒体中的另一种铁源（主要富含⁵⁷ Fe）被用来输出最终掺入胞浆蛋白中的物种。缓冲液中的铁输入线粒体最快，其次是线粒体 ISC 组装、LMM 铁输出和胞质 ISC 组装。

更新日期：2023-06-20

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