Rogov A G, Zvyagilskaya R A
Bach Institute of Biochemistry, Russian Academy of Sciences, Moscow, 119071, Russia.
Biochemistry (Mosc). 2015 Apr;80(4):400-7. doi: 10.1134/S0006297915040021.
Mitochondria of all so far studied organisms, with the exception of Archaea, mammals, some yeasts, and protists, contain, along with the classical phosphorylating cytochrome pathway, a so-called cyanide-insensitive alternative oxidase (AOX) localized on the matrix side of the mitochondrial inner membrane, and electron transport through which is not coupled with ATP synthesis and energy accumulation. Mechanisms underlying plentiful functions of AOX in organisms at various levels of organization ranging from yeasts to plants are considered. First and foremost, AOX provides a chance of cell survival after inhibiting the terminal components of the main respiratory chain or losing the ability to synthesize these components. The vitally important role of AOX is obvious in thermogenesis of thermogenic plant organs where it becomes the only terminal oxidase with a very high activity, and the energy of substrate oxidation by this respiratory pathway is converted into heat, thus promoting evaporation of volatile substances attracting pollinating insects. AOX plays a fundamentally significant role in alleviating or preventing oxidative stress, thus ensuring the defense against a wide range of stresses and adverse environmental conditions, such as changes in temperature and light intensities, osmotic stress, drought, and attack by incompatible strains of bacterial pathogens, phytopathogens, or their elicitors. Participation of AOX in pathogen survival during its existence inside the host, in antivirus defense, as well as in metabolic rearrangements in plants during embryogenesis and cell differentiation is described. Examples are given to demonstrate that AOX might be an important tool to overcome the adverse aftereffects of restricted activity of the main respiratory chain in cells and whole animals.
除古细菌、哺乳动物、某些酵母和原生生物外，目前所有已研究生物的线粒体，除了经典的磷酸化细胞色素途径外，还含有一种所谓的对氰化物不敏感的交替氧化酶（AOX），它位于线粒体内膜的基质侧，通过其进行的电子传递不与ATP合成和能量积累相偶联。本文探讨了AOX在从酵母到植物等不同组织层次的生物体中发挥多种功能的潜在机制。首先，AOX为细胞在抑制主要呼吸链的末端成分或失去合成这些成分的能力后提供了存活的机会。AOX在产热植物器官的产热过程中起着至关重要的作用，在这些器官中它成为唯一具有非常高活性的末端氧化酶，通过这种呼吸途径氧化底物产生的能量转化为热量，从而促进吸引传粉昆虫的挥发性物质的蒸发。AOX在减轻或预防氧化应激方面发挥着根本性的重要作用，从而确保对各种胁迫和不利环境条件的防御，如温度和光照强度的变化、渗透胁迫、干旱以及不相容的细菌病原体、植物病原体或其激发子的攻击。本文还描述了AOX在病原体在宿主体内存活期间的参与情况、在抗病毒防御中的作用，以及在植物胚胎发生和细胞分化过程中的代谢重排。文中给出了一些例子来说明AOX可能是克服细胞和整个动物主要呼吸链活性受限所带来的不良后果的重要工具。
