School of Biosciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, UK.
J Exp Bot. 2024 Aug 12;75(15):4599-4610. doi: 10.1093/jxb/erae090.
The superoxide anion radical (O2·-) is a one-electron reduction product of molecular oxygen. Compared with other forms of reactive oxygen species (ROS), superoxide has limited reactivity. Nevertheless, superoxide reacts with nitric oxide, ascorbate, and the iron moieties of [Fe-S] cluster-containing proteins. Superoxide has largely been neglected as a signalling molecule in the plant literature in favour of the most stable ROS form, hydrogen peroxide. However, superoxide can accumulate in plant cells, particularly in meristems, where superoxide dismutase activity and ascorbate accumulation are limited (or absent), or when superoxide is generated within the lipid environment of membranes. Moreover, oxidation of the nucleus in response to environmental stresses is a widespread phenomenon. Superoxide is generated in many intracellular compartments including mitochondria, chloroplasts, and on the apoplastic/cell wall face of the plasma membrane. However, nuclear superoxide production and functions remain poorly documented in plants. Accumulating evidence suggests that the nuclear pools of antioxidants such as glutathione are discrete and separate from the cytosolic pools, allowing compartment-specific signalling in the nucleus. We consider the potential mechanisms of superoxide generation and targets in the nucleus, together with the importance of antioxidant processing in regulating superoxide signalling.
超氧阴离子自由基 (O2·-) 是分子氧的单电子还原产物。与其他形式的活性氧 (ROS) 相比，超氧自由基的反应性有限。然而，超氧自由基会与一氧化氮、抗坏血酸和含 [Fe-S] 簇蛋白的铁部分反应。在植物文献中，超氧自由基作为一种信号分子在很大程度上被忽视，而倾向于最稳定的 ROS 形式，即过氧化氢。然而，超氧自由基可以在植物细胞中积累，特别是在分生组织中，那里的超氧化物歧化酶活性和抗坏血酸积累受到限制（或不存在），或者当超氧自由基在膜的脂质环境中产生时。此外，核氧化作为对环境胁迫的响应是一种广泛存在的现象。超氧自由基在许多细胞内隔室中产生，包括线粒体、叶绿体和质膜的质外体/细胞壁面。然而，植物中核超氧自由基的产生和功能仍然记录甚少。越来越多的证据表明，抗氧化剂如谷胱甘肽的核池与细胞质池是离散的和分开的，允许在核中进行特定于隔室的信号传递。我们考虑了超氧自由基在核中的产生和靶标潜在机制，以及抗氧化剂处理在调节超氧自由基信号中的重要性。
