Alternative oxidases in animals

动物体内的替代氧化酶

• 批准号: RGPIN-2022-03570
• 负责人: McDonald, Allison
• 金额: $ 2.04万
• 依托单位: Wilfrid Laurier University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=745810
• 关键词: Alternative; oxidases; animals

The currency of life on Earth is energy. Living organisms use electron transport systems (ETS) to convert various molecules into adenosine triphosphate (ATP) for growth and reproduction. Cytochrome c oxidase is the final electron acceptor in most ETS, but many organisms also contain a second terminal oxidase called alternative oxidase (AOX). The physiological role for AOX is rather mysterious, as its presence seems counterintuitive from a bioenergetics perspective, but AOX mRNA expression and AOX protein levels increase during stress. These observations suggest that AOX confers flexibility in the ETS and allows organisms to deal with stressful environments. AOX, initially thought to be absent from animals, was discovered in animals in 2005. This new field of research has been explored since then, but there are still significant gaps in our knowledge. I propose to address three main questions that form the basis of my research program. (1) How is AOX post-translationally regulated in animals? Very few studies have looked at a natural AOX protein in animals. The AOX protein is present in several animal species, but our knowledge of the post-translational regulation of the protein's activity in animals is lacking. We will study this process in the copepod Tigriopus californicus, as my lab has spent several years developing tools to study AOX in this organism. We will use high-resolution respirometry to identify the activators and inhibitors of AOX, as well as the impact of potential respiratory substrates on the capacity of this pathway. (2) What is the physiological role(s) of AOX in animals? AOX in plants contributes significantly to stress tolerance by allowing flexibility in the ETS for effective regulation of ATP demand and carbon flux through primary metabolism. Perhaps AOX plays a similar physiological role in animals. We will manipulate the levels of AOX protein in Tigriopus californicus and then will expose these animals to high temperature stress to see if AOX plays a role in their survival under these conditions. (3) What is the taxonomic distribution of AOX in animals? This is a continuing goal of my research program, as it is impossible to study AOX unless we can identify which animals contain it. This work is done by using a combination of bioinformatics analyses to identify animals that contain AOX, followed by molecular biology experiments to confirm the expression of AOX mRNA and the presence of AOX protein in these species. A better understanding of the taxonomic distribution of AOX will contribute to our knowledge on the origin and evolutionary history of the enzyme. The knowledge gained from our research may lead to treatments for human mitochondrial diseases and human infections caused by parasitic animals. Targeting AOX using inhibitors may allow us to kill parasites that threaten Canadian agriculture and aquaculture.

地球上生命的货币是能量。生物利用电子传输系统(ETS)将各种分子转化为三磷酸腺苷(ATP)进行生长和繁殖。细胞色素c氧化酶是大多数ETS的最终电子受体，但许多生物也含有第二末端氧化酶，称为交替氧化酶(AOX)。AOX的生理作用相当神秘，因为从生物能量学的角度来看，它的存在似乎是违反直觉的，但AOX的mRNA表达和AOX蛋白水平在应激过程中会增加。这些观察表明，AOX在ETS中赋予了灵活性，并允许有机体处理压力环境。AOX最初被认为不存在于动物体内，于2005年在动物体内被发现。从那时起，这一新的研究领域一直在探索，但我们的知识仍然存在重大差距。我建议解决三个主要问题，这三个问题构成了我研究计划的基础。(1)AOX在动物体内是如何翻译后调控的？很少有研究关注动物体内的天然AOX蛋白。AOX蛋白存在于几个动物物种中，但我们对该蛋白在动物体内的翻译后活性调节缺乏了解。由于我的实验室花了几年时间开发工具来研究这种有机体中的AOX，我们将在桡足类恐龙身上研究这一过程。我们将使用高分辨率呼吸测量法来确定AOX的激活剂和抑制剂，以及潜在的呼吸底物对这一途径容量的影响。(2)AOX在动物体内的生理作用(S)是什么？植物中的AOX通过允许ETS的灵活性，通过初级代谢有效地调节ATP需求和碳通量，从而显著提高了植物的逆境耐受性。也许AOX在动物身上也扮演着类似的生理角色。我们将操纵加州虎鱼中AOX蛋白的水平，然后将这些动物暴露在高温应激中，看看AOX在这些条件下是否对它们的生存起到作用。(3)AOX在动物体内的分类分布是什么？这是我的研究项目的一个持续目标，因为除非我们能确定哪些动物含有AOX，否则不可能研究AOX。这项工作是通过结合生物信息学分析来识别含有AOX的动物，然后通过分子生物学实验来确认AOX mRNA的表达和AOX蛋白在这些物种中的存在。更好地了解AOX的分类分布将有助于我们了解AOX的起源和进化史。从我们的研究中获得的知识可能会导致治疗人类线粒体疾病和由寄生虫动物引起的人类感染。使用抑制剂靶向AOX可能会让我们杀死威胁加拿大农业和水产养殖业的寄生虫。