Magnetic Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, 50019, Sesto Fiorentino, Florence, Italy.
Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019, Sesto Fiorentino, Florence, Italy.
Sci Rep. 2019 Dec 12;9(1):18986. doi: 10.1038/s41598-019-55313-5.
In mitochondria, a complex protein machinery is devoted to the maturation of iron-sulfur cluster proteins. Structural information on the last steps of the machinery, which involve ISCA1, ISCA2 and IBA57 proteins, needs to be acquired in order to define how these proteins cooperate each other. We report here the use of an integrative approach, utilizing information from small-angle X-ray scattering (SAXS) and bioinformatics-driven docking prediction, to determine a low-resolution structural model of the human mitochondrial [2Fe-2S] ISCA2-IBA57 complex. In the applied experimental conditions, all the data converge to a structural organization of dimer of dimers for the [2Fe-2S] ISCA2-IBA57 complex with ISCA2 providing the homodimerization core interface. The [2Fe-2S] cluster is out of the ISCA2 core while being shared with IBA57 in the dimer. The specific interaction pattern identified from the dimeric [2Fe-2S] ISCA2-IBA57 structural model allowed us to define the molecular grounds of the pathogenic Arg146Trp mutation of IBA57. This finding suggests that the dimeric [2Fe-2S] ISCA2-IBA57 hetero-complex is a physiologically relevant species playing a role in mitochondrial [4Fe-4S] protein biogenesis.
在线粒体中，一套复杂的蛋白质机器致力于铁硫簇蛋白的成熟。为了定义这些蛋白质如何相互合作，需要获得关于涉及 ISCA1、ISCA2 和 IBA57 蛋白的机器最后步骤的结构信息。在这里，我们报告了一种综合方法的使用，该方法利用小角度 X 射线散射 (SAXS) 和基于生物信息学的对接预测的信息，来确定人线粒体 [2Fe-2S] ISCA2-IBA57 复合物的低分辨率结构模型。在应用的实验条件下，所有数据都收敛到 [2Fe-2S] ISCA2-IBA57 复合物的二聚体二聚体的结构组织，其中 ISCA2 提供同源二聚体核心界面。[2Fe-2S]簇不在 ISCA2 核心内，而是与二聚体中的 IBA57 共享。从二聚体 [2Fe-2S] ISCA2-IBA57 结构模型中识别出的特定相互作用模式使我们能够定义 IBA57 的致病性 Arg146Trp 突变的分子基础。这一发现表明，二聚体 [2Fe-2S] ISCA2-IBA57 异源复合物是一种生理相关的物质，在线粒体 [4Fe-4S] 蛋白生物发生中发挥作用。
