CERM, University of Florence, Via L Sacconi 9, 50019 Sesto Fiorentino, Italy.
Int J Mol Sci. 2024 Jan 18;25(2):1174. doi: 10.3390/ijms25021174.
MIA40 and ALR of the MIA pathway mediate the import of protein precursors that form disulfides into the mitochondrial intermembrane space. This import pathway is suggested to be a linear pathway in which MIA40 first binds to the precursor via a disulfide linkage and oxidizes it. Subsequently, ALR re-oxidizes MIA40 and then ALR transfers electrons to terminal electron acceptors. However, the precise mechanism by which ALR and MIA40 coordinate translocation is unknown. With a collection of small molecule modulators (MB-5 to MB-9 and MB-13) that inhibit ALR activity, we characterized the import mechanism in mitochondria. NMR studies show that most of the compounds bind to a similar region in ALR. Mechanistic studies with small molecules demonstrate that treatment with compound MB-6 locks the precursor in a state bound to MIA40, blocking re-oxidation of MIA40 by ALR. Thus, small molecules that target a similar region in ALR alter the dynamics of the MIA import pathway differently, resulting in a set of probes that are useful for studying the catalysis of the redox-regulated import pathway in model systems.
MIA40 和 ALR 介导形成二硫键的蛋白前体进入线粒体膜间隙的导入途径。该导入途径被认为是一条线性途径，其中 MIA40 首先通过二硫键与前体结合并使其氧化。随后，ALR 重新氧化 MIA40，然后 ALR 将电子转移到末端电子受体。然而，ALR 和 MIA40 协调易位的确切机制尚不清楚。我们利用一系列小分子调节剂（MB-5 至 MB-9 和 MB-13）抑制 ALR 活性，对线粒体中的导入机制进行了表征。NMR 研究表明，大多数化合物结合到 ALR 的相似区域。用小分子进行的机制研究表明，用化合物 MB-6 处理会将前体锁定在与 MIA40 结合的状态，阻止 ALR 对 MIA40 的再氧化。因此，靶向 ALR 相似区域的小分子以不同的方式改变 MIA 导入途径的动力学，产生了一组探针，可用于在模型系统中研究氧化还原调节导入途径的催化作用。
