Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA; Department of Molecular Biology, Universitätsmedizin Göttingen, 37073 Göttingen, Germany.
Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA.
Mol Cell. 2014 Oct 2;56(1):116-27. doi: 10.1016/j.molcel.2014.08.017. Epub 2014 Sep 18.
Exposure of cells to reactive oxygen species (ROS) causes a rapid and significant drop in intracellular ATP levels. This energy depletion negatively affects ATP-dependent chaperone systems, making ROS-mediated protein unfolding and aggregation a potentially very challenging problem. Here we show that Get3, a protein involved in ATP-dependent targeting of tail-anchored (TA) proteins under nonstress conditions, turns into an effective ATP-independent chaperone when oxidized. Activation of Get3's chaperone function, which is a fully reversible process, involves disulfide bond formation, metal release, and its conversion into distinct, higher oligomeric structures. Mutational studies demonstrate that the chaperone activity of Get3 is functionally distinct from and likely mutually exclusive with its targeting function, and responsible for the oxidative stress-sensitive phenotype that has long been noted for yeast cells lacking functional Get3. These results provide convincing evidence that Get3 functions as a redox-regulated chaperone, effectively protecting eukaryotic cells against oxidative protein damage.
细胞暴露于活性氧(ROS)会导致细胞内 ATP 水平迅速显著下降。这种能量耗竭会对依赖 ATP 的伴侣系统产生负面影响,使 ROS 介导的蛋白质展开和聚集成为一个潜在的非常具有挑战性的问题。在这里,我们表明,Get3 是一种在非应激条件下参与靶向尾部锚定(TA)蛋白的 ATP 依赖性的蛋白,当它被氧化时,会变成一种有效的非依赖于 ATP 的伴侣。Get3 的伴侣功能的激活是一个完全可逆的过程,涉及二硫键形成、金属释放以及其转化为不同的、更高的寡聚结构。突变研究表明,Get3 的伴侣活性与其靶向功能在功能上是不同的,可能是相互排斥的,并且负责酵母细胞中缺乏功能性 Get3 时长期存在的氧化应激敏感表型。这些结果提供了令人信服的证据,表明 Get3 作为一种氧化还原调节伴侣发挥作用,有效地保护真核细胞免受氧化蛋白损伤。