Hypothesized Evolutionary Consequences of the Alternative Oxidase (AOX) in Animal Mitochondria
Hypothesized Evolutionary Consequences of the Alternative Oxidase (AOX) in Animal Mitochondria
复制标题
动物线粒体中替代氧化酶（AOX）的假设进化后果
DOI：
10.1093/icb/icz015
复制
发表时间：
2019
影响因子：
2.6
通讯作者：
Weaver, Ryan J
中科院分区：
文献类型：
--
作者：
Weaver, Ryan J
真核生物最初进化的环境与今天的环境截然不同，其中一个关键的限制因素是线粒体呼吸所需的氧气。在过渡到一个完全含氧的地球，其他化合物，如硫化物构成了相当大的限制使用线粒体有氧呼吸能量生产。动物的祖先，以及那些最初从简单的真核生物进化而来的动物，具有线粒体呼吸成分，而这些成分在后来进化的动物中是不存在的。具体而言，大多数基础后生动物的线粒体具有抗硫化物的交替氧化酶（AOX），其提供了经典细胞色素途径的次级氧化途径。在这篇文章中，我认为，由于其耐硫化物，AOX呼吸是至关重要的动物的进化，使氧化代谢下，否则抑制条件。我假设AOX允许代谢的灵活性，在随机氧气环境的早期地球形成的进化基础后生动物。我简要介绍了AOX的已知功能，特别关注在应激条件下活性氧（ROS）的产生减少。然后，我提出了三个进化的后果AOX介导的保护ROS观察到的基础后生动物：1）适应压力环境，2）兼性有性生殖的持久性，和3）线粒体DNA突变率下降。认识到动物线粒体呼吸系统的多样性可能有助于解决主要进化过程中所涉及的机制，如适应和物种形成。
The environment in which eukaryotes first evolved was drastically different from what they experience today, and one of the key limiting factors was the availability of oxygen for mitochondrial respiration. During the transition to a fully oxygenated Earth, other compounds such as sulfide posed a considerable constraint on using mitochondrial aerobic respiration for energy production. The ancestors of animals, and those that first evolved from the simpler eukaryotes have mitochondrial respiratory components that are absent from later-evolving animals. Specifically, mitochondria of most basal metazoans have a sulfide-resistant alternative oxidase (AOX), which provides a secondary oxidative pathway to the classical cytochrome pathway. In this essay, I argue that because of its resistance to sulfide, AOX respiration was critical to the evolution of animals by enabling oxidative metabolism under otherwise inhibitory conditions. I hypothesize that AOX allowed for metabolic flexibility during the stochastic oxygen environment of early Earth which shaped the evolution of basal metazoans. I briefly describe the known functions of AOX, with a particular focus on the decreased production of reactive oxygen species (ROS) during stress conditions. Then, I propose three evolutionary consequences of AOX-mediated protection from ROS observed in basal metazoans: 1) adaptation to stressful environments, 2) the persistence of facultative sexual reproduction, and 3) decreased mitochondrial DNA mutation rates. Recognizing the diversity of mitochondrial respiratory systems present in animals may help resolve the mechanisms involved in major evolutionary processes such as adaptation and speciation.