Institut für Biochemie und Molekularbiologie, Universität Bonn, Bonn, Germany.
Proteomics. 2010 Apr;10(7):1426-43. doi: 10.1002/pmic.200800619.
Mitochondria contribute significantly to the cellular production of ROS. The deleterious effects of increased ROS levels have been implicated in a wide variety of pathological reactions. Apart from a direct detoxification of ROS molecules, protein quality control mechanisms are thought to protect protein functions in the presence of elevated ROS levels. The reactivities of molecular chaperones and proteases remove damaged polypeptides, maintaining enzyme activities, thereby contributing to cellular survival both under normal and stress conditions. We characterized the impact of oxidative stress on mitochondrial protein homeostasis by performing a proteomic analysis of isolated yeast mitochondria, determining the changes in protein abundance after ROS treatments. We identified a set of mitochondrial proteins as substrates of ROS-dependent proteolysis. Enzymes containing oxidation-sensitive prosthetic groups like iron/sulfur clusters represented major targets of stress-dependent degradation. We found that several proteins involved in ROS detoxification were also affected. We identified the ATP-dependent protease Pim1/LON as a major factor in the degradation of ROS-modified soluble polypeptides localized in the matrix compartment. As Pim1/LON expression was induced significantly under ROS treatment, we propose that this protease system performs a crucial protective function under oxidative stress conditions.
线粒体对细胞内 ROS 的产生有重要贡献。ROS 水平升高的有害影响与多种病理反应有关。除了直接清除 ROS 分子外，蛋白质质量控制机制被认为可以在 ROS 水平升高的情况下保护蛋白质的功能。分子伴侣和蛋白酶的反应性去除受损的多肽，保持酶的活性，从而有助于细胞在正常和应激条件下的存活。我们通过对分离的酵母线粒体进行蛋白质组学分析来研究氧化应激对线粒体蛋白质稳态的影响，确定 ROS 处理后蛋白质丰度的变化。我们鉴定了一组作为 ROS 依赖性蛋白水解底物的线粒体蛋白。含有氧化敏感辅基（如铁/硫簇）的酶是应激依赖性降解的主要靶标。我们发现，几种参与 ROS 解毒的蛋白质也受到影响。我们鉴定了依赖 ATP 的蛋白酶 Pim1/LON 是降解定位于基质区室中的 ROS 修饰可溶性多肽的主要因素。由于 ROS 处理后 Pim1/LON 的表达明显增加，我们提出该蛋白酶系统在氧化应激条件下发挥关键的保护功能。
