Probing the molecular basis of oxygen reduction by the alternative oxidases

探索替代氧化酶还原氧的分子基础

• 批准号: BB/L022915/1
• 负责人: Anthony Moore
• 金额: $ 34.42万
• 依托单位: University of Sussex
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2014
• 资助国家: 英国
• 起止时间: 2014 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FL022915%2F1
• 关键词: Probing; molecular; basis; oxygen; reduction

Enzymes are proteins that facilitate the reactions that enable living organisms to acquire energy for growth, reproduction and maintenance. A key challenge in understanding the structure-function relationship of one such group of enzymes, the alternative oxidases (AOX), rests upon the identification of its substrate and inhibitor-binding site and its mechanism of action. A detailed knowledge of the nature of this binding site is important since it will reveal whether or not there is a common architecture that can be applied to substrate and inhibitor-binding sites in general and hence provide an insight into the mechanism of binding. More importantly, this knowledge will assist in the suitable rational design of phytopathogenic and anti-parasitic drugs that are specifically targeted to the alternative oxidase. It is now recognized that the distribution of the alternative oxidase is substantially wider than previously thought. No longer restricted to plants, some fungi and protists, the alternative oxidase is also widespread amongst human parasites such as Trypanosoma brucei (the causative agent of African sleeping sickness), intestinal parasites such as Cryptosporidium parvum (responsible for an airborne intestinal infection cryptosporidiosis) and opportunistic human pathogens such as Candida albicans (causes candidiasis or 'thrush'). With respect to the role of AOX in fungi, the development of resistance to agrochemicals by plant fungal pathogens is an international problem that affects all major crops. Indeed fungicide resistance is an important factor in the successful cultivation of cereals in the UK. It is estimated that the UK market for fungicides in cereals is approximately £200m (worldwide $3bn) with winter wheat being the main crop. Fungicides are used against a number of diseases, the major one of winter wheat being caused by Septoria tritici. The main chemical classes of fungicides used to treat UK cereals include the sterol biosynthesis inhibitors. The most important and successful group of these fungicides that have proved effective in the control of plant pathogens are the strobilurin fungicides which are specifically targeted to the mitochondrial respiratory chain (Qo site) thereby inhibiting fungal respiration. Unfortunately resistance to this fungicide often develops resulting in an inability to control fungal pathogens through continued application. Although the mechanism for conferring resistance to Qo fungicides is still controversial there is growing evidence to suggest that the addition of inhibitors, such as azoxystrobin, to fungal pathogens results in a strong induction of the alternative oxidase (AOX). AOX is a mitochondrial terminal oxidase which by-passes the Qo site and is induced in all plants, fungal pathogens and protists following stress induction. We have previously demonstrated that fungal plant pathogens such as Septoria tritici, a fungus that causes major leaf spot diseases in wheat & the wheat "Take-all" fungus, Gaeumannomyces graminis var. tritici have the capacity to express an alternative oxidase when treated with respiratory inhibitors thereby allowing a strobilurin-resistant respiratory pathway to develop which may account for the varying efficacy of strobilurin fungicides. The objectives of the present study are to gain further detailed structural knowledge of the mechanism of oxygen reduction, the nature of the protein-ligand interaction and kinetics through the use of mutants and in the presence and absence of inhibitors. Such information will also be important for further catalytic tuning of the alternative oxidases for future gene therapy strategies and will place us in a very powerful position to undertake future rational inhibitor design which will act as specific and potent phytopathogenic and anti-parasitic drugs specifically targeted at the AOX.

酶是一种促进反应的蛋白质，使生物体能够获得生长、繁殖和维持所需的能量。要了解其中一类酶，即替代氧化酶（AOX）的结构-功能关系，一个关键的挑战在于鉴定其底物和抑制剂结合位点及其作用机制。对这种结合位点性质的详细了解是很重要的，因为它将揭示是否存在一种可以应用于底物和抑制剂结合位点的通用结构，从而提供对结合机制的深入了解。更重要的是，这些知识将有助于适当合理地设计专门针对替代氧化酶的植物致病和抗寄生虫药物。现在人们认识到，替代氧化酶的分布比以前认为的要广泛得多。替代氧化酶不再局限于植物、一些真菌和原生生物，它也广泛存在于人类寄生虫中，如布氏锥虫（非洲昏睡病的病原体）、肠道寄生虫，如细小隐孢子虫（导致空气传播的肠道感染隐孢子虫病）和机会性人类病原体，如白色念珠菌（引起念珠菌病或鹅口疮）。关于AOX在真菌中的作用，植物真菌病原体对农用化学品产生抗性是一个影响所有主要作物的国际问题。事实上，抗杀菌剂是英国谷物种植成功的一个重要因素。据估计，英国谷物杀菌剂市场约为2亿英镑（全球30亿美元），冬小麦是主要作物。杀菌剂用于防治多种病害，其中冬小麦的主要病害是由黑穗病引起的。用于处理英国谷物的杀菌剂的主要化学类别包括甾醇生物合成抑制剂。这些杀菌剂中最重要和最成功的一类是strobilurin杀菌剂，它专门针对线粒体呼吸链（Qo位点），从而抑制真菌的呼吸作用。不幸的是，对这种杀菌剂的耐药性经常发展导致无法通过继续使用来控制真菌病原体。尽管对Qo杀菌剂产生耐药性的机制仍存在争议，但越来越多的证据表明，在真菌病原体中添加抑制剂（如偶氮嘧菌酯）会导致选择性氧化酶（AOX）的强烈诱导。AOX是一种线粒体末端氧化酶，绕过Qo位点，在所有植物、真菌病原体和原生生物中都能被诱导。我们之前已经证明，真菌植物病原体，如小麦Septoria tritici（一种引起小麦主要叶斑病的真菌）和小麦“全食”真菌Gaeumannomyces graminis var. tritici，在使用呼吸抑制剂处理时，具有表达替代氧化酶的能力，从而允许抗strobilurin的呼吸途径发展，这可能解释了strobilurin杀菌剂的不同功效。本研究的目标是通过使用突变体和抑制剂的存在和不存在，获得进一步详细的氧还原机制结构知识，蛋白质-配体相互作用的性质和动力学。这些信息对于未来基因治疗策略的替代氧化酶的进一步催化调整也很重要，并将使我们处于一个非常强大的位置，以进行未来合理的抑制剂设计，这些抑制剂将作为特异性和有效的植物致病性和抗寄生虫药物，专门针对AOX。

项目成果

QSAR and molecular docking for the search of AOX inhibitors: a rational drug discovery approach.

• DOI: 10.1007/s10822-020-00360-8
• 发表时间: 2021-03
• 期刊: Journal of computer-aided molecular design
• 影响因子: 3.5
• 作者: Rosell-Hidalgo A;Young L;Moore AL;Ghafourian T
• 通讯作者: Ghafourian T

Alternative respiratory pathways in higher plants

高等植物的替代呼吸途径

• DOI: 10.1002/9781118789971.ch5
• 发表时间: 2015
• 作者: Elliott C

A Self-Assembled Respiratory Chain that Catalyzes NADH Oxidation by Ubiquinone-10 Cycling between Complex I and the Alternative Oxidase

通过泛醌-10 在复合物 I 和替代氧化酶之间循环催化 NADH 氧化的自组装呼吸链

• DOI: 10.1002/ange.201507332
• 发表时间: 2015
• 期刊: Angewandte Chemie
• 作者: Jones A

Degradation of mitochondrial alternative oxidase in the appendices of Arum maculatum.

• DOI: 10.1042/bcj20200515
• 发表时间: 2020-09-18
• 期刊: The Biochemical journal
• 作者: Ito K;Ogata T;Seito T;Umekawa Y;Kakizaki Y;Osada H;Moore AL
• 通讯作者: Moore AL

Kinetic characterisation and inhibitor sensitivity of Candida albicans and Candida auris recombinant AOX expressed in a self-assembled proteoliposome system.

• DOI: 10.1038/s41598-021-94320-3
• 发表时间: 2021-07-20
• 期刊: Scientific reports
• 影响因子: 4.6
• 作者: Copsey AC;Barsottini MRO;May B;Xu F;Albury MS;Young L;Moore AL
• 通讯作者: Moore AL