Interfaces, Traitements, Organisation et Dynamique des Systèmes (ITODYS), CNRS UMR 7086, Univ Paris Diderot, Sorbonne Paris Cité, 15 rue Jean-Antoine de Baïf, F-75205 Paris Cedex 13, France.
Mitochondries, Métaux et Stress Oxydant, Institut Jacques Monod, CNRS UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, 15 rue Hélène Brion, F-75205 Paris Cedex 13, France.
Biochim Biophys Acta Gen Subj. 2019 May;1863(5):883-892. doi: 10.1016/j.bbagen.2019.02.011. Epub 2019 Feb 21.
Friedreich's ataxia results from a decreased expression of the nuclear gene encoding the mitochondrial protein, frataxin. Frataxin participates in the biosynthesis of iron-sulfur clusters and heme cofactors, as well as in iron storage and protection against oxidative stress. How frataxin interacts with the antioxidant defence components is poorly understood.
Therefore, we have investigated by kinetic, thermodynamic and modelling approaches the molecular interactions between yeast frataxin (Yfh1) and superoxide dismutases, Sod1 and Sod2, and the influence of Yfh1 on their enzymatic activities.
Yfh1 interacts with cytosolic Sod1 with a dissociation constant, K = 1.3 ± 0.3 μM, in two kinetic steps. The first step occurs in the 200 ms range and corresponds to the Yfh1-Sod1 interaction, whereas the second is slow and is assumed to be a change in the conformation of the protein-protein adduct. Furthermore, computational investigations confirm the stability of the Yfh1-Sod1 complex. Yfh1 forms two protein complexes with mitochondrial Sod2 with 1:1 and 2:1 Yfh1/Sod2 stoichiometry (K = 1.05 ± 0.05 and K = 6.6 ± 0.1 μM). Furthermore, Yfh1 increases the enzymatic activity of Sod1 while slightly affecting that of Sod2. Finally, the stabilities of the protein-protein adducts and the effect of Yfh1 on superoxide dismutase activities depend on the nature of the mitochondrial metal.
This work confirms the participation of Yfh1 in cellular defence against oxidative stress.
弗里德赖希共济失调是由于核基因编码的线粒体蛋白 frataxin 表达减少引起的。Frataxin 参与铁硫簇和血红素辅因子的生物合成，以及铁的储存和抗氧化应激的保护。Frataxin 如何与抗氧化防御成分相互作用还知之甚少。
因此，我们通过动力学、热力学和建模方法研究了酵母 frataxin (Yfh1) 与超氧化物歧化酶 Sod1 和 Sod2 之间的分子相互作用，以及 Yfh1 对它们酶活性的影响。
Yfh1 与细胞质 Sod1 以解离常数 K=1.3±0.3μM 在两个动力学步骤中相互作用。第一步发生在 200ms 范围内，对应于 Yfh1-Sod1 相互作用，而第二步较慢，假定是蛋白质-蛋白质加合物构象的变化。此外，计算研究证实了 Yfh1-Sod1 复合物的稳定性。Yfh1 与线粒体 Sod2 形成两种 1:1 和 2:1 的蛋白质复合物（K=1.05±0.05 和 K=6.6±0.1μM）。此外，Yfh1 增加了 Sod1 的酶活性，而对 Sod2 的活性影响较小。最后，蛋白质-蛋白质加合物的稳定性和 Yfh1 对超氧化物歧化酶活性的影响取决于线粒体金属的性质。
这项工作证实了 Yfh1 参与细胞对抗氧化应激的防御。
