Directed Evolution of Photosystem Chemistry

光系统化学的定向进化

• 批准号: MR/T017546/2
• 负责人: Tanai Cardona Londono
• 金额: $ 28.76万
• 依托单位: Queen Mary University of London
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=MR%2FT017546%2F2
• 关键词: Directed; Evolution; Photosystem; Chemistry

The importance of photosynthesis for the evolution of life can hardly be overemphasised. It represents one of the key innovations that transformed Earth and paved the way for the rise of complex life.Today, the improvement of photosynthesis to enhance crops and the production of compounds of commercial interest has become one of the grand challenges of photosynthesis research.To improve photosynthesis, it is necessary to change photosynthesis. The study of the evolution of photosynthesis is the study of how photosynthesis has changed through time, which has been the focus of my research. The study of the evolution of photosynthesis can provide relevant insight on its potential for change, optimisation, or improvement.For example, my research has shown that in several occasions through geological time, the chemistry of oxygenic photosynthesis was rapidly and radically optimised to match environments with very atypical light conditions such as those found at 200 meter-deep open ocean waters or within stromatolites. This indicated that the process has a level of plasticity and potential for adaptability well beyond what is currently recognised.I want to link my research on the evolution of photosynthesis with Directed Evolution methods to experimentally prove that it is possible to control and purposefully change the chemistry of photosynthesis.Directed Evolution is an extremely versatile method that is used to change the traits or the activity of a given enzyme by exploiting evolution. It can be done simply by subjecting an organism through repeated cycles of selection under the conditions that favour the desired traits, it can be enhanced by turbocharging mutational rates, it can be focused on a single gene of interest, and it can be combined with another method called Ancestral Sequence Reconstruction (ASR).ASR is an evolutionary method commonly used to compute the most likely ancestral state of an enzyme. The ancestral enzyme gene can then be made using commercially available services and used to study the properties of the ancestral enzyme in the test tube. An interesting outcome of ASR is that the ancestral enzymes show superior stability and functional flexibility. These properties have made the combination of ASR and Directed Evolution a powerful biotechnological tool.I currently lead a research programme on the molecular evolution of photosynthesis and this employs ASR to reconstruct the ancestral states of Photosystem II.Photosystems are nature's solar cells and they power life on Earth by converting light into useful chemical energy. They have done so for billions of years. Photosystem II uses light to decompose water into oxygen, protons, and to generate an electric current. This is the hallmark chemical reaction of oxygenic photosynthesis.The photosystems are very complex molecular machines. This complexity means that they evolve very slowly. It is often believed that they exist as "frozen metabolic accidents". A concept that was introduced to imply that these systems have reached a maximum level of optimal performance and therefore have limited evolvability: in other words, it is thought that they cannot be changed in any way that is useful. This view is however contradicted by my own work, which instead suggests the photosystems have tremendous natural adaptability potential.My research group aims to demonstrate that the function of the photosystems can be changed and controlled in any desirable way with the use of Directed Evolution. We will demonstrate that the function of the photosystems can be optimised to any particular condition given an appropriate set of selective pressures. We will provide tools and a molecular blueprint for the control and optimisation of photosystem chemistry for potential future molecular applications.

光合作用对生命进化的重要性怎么强调都不过分。它代表了改变地球的关键创新之一为复杂生命的出现铺平了道路。今天，改善光合作用以增强作物和生产具有商业价值的化合物已成为光合作用研究的重大挑战之一。为了改善光合作用，必须改变光合作用。研究光合作用的进化就是研究光合作用是如何随着时间的推移而变化的，这一直是我研究的重点。对光合作用进化的研究可以为其变化、优化或改进的潜力提供相关的见解。例如，我的研究表明，在地质时代的几个场合，氧光合作用的化学反应被迅速而彻底地优化，以匹配非常非典型的光照条件，例如在200米深的开阔海域或叠层石中发现的环境。这表明，这一过程的可塑性和适应性潜力远远超出了目前所认识的水平。我想把我对光合作用进化的研究与定向进化方法联系起来，通过实验证明控制和有目的地改变光合作用的化学性质是可能的。定向进化是一种非常通用的方法，用于通过利用进化来改变特定酶的特征或活性。它可以简单地通过在有利于期望性状的条件下对生物体进行重复的选择循环来完成，它可以通过提高突变率来增强，它可以集中在感兴趣的单个基因上，它可以与另一种称为祖先序列重建（ASR）的方法相结合。ASR是一种通常用于计算酶最可能的祖先状态的进化方法。然后，可以使用商业上可用的服务制作祖先酶基因，并用于在试管中研究祖先酶的特性。ASR的一个有趣的结果是，祖先酶表现出优越的稳定性和功能灵活性。这些特性使得ASR和定向进化的结合成为一种强大的生物技术工具。我目前正在领导一个关于光合作用分子进化的研究项目，这个项目利用ASR来重建光系统II的祖先状态。光系统是自然界的太阳能电池，它们通过将光转化为有用的化学能，为地球上的生命提供能量。它们这样做了几十亿年。光系统II利用光将水分解成氧气、质子并产生电流。这是含氧光合作用的典型化学反应。光系统是非常复杂的分子机器。这种复杂性意味着它们的进化非常缓慢。人们通常认为它们是以“冰冻代谢事故”的形式存在的。这个概念的引入是为了暗示这些系统已经达到了最佳性能的最大水平，因此具有有限的可进化性：换句话说，它被认为不能以任何有用的方式改变它们。然而，这种观点与我自己的工作相矛盾，相反，我的工作表明光系统具有巨大的自然适应性潜力。我的研究小组旨在证明光系统的功能可以通过使用定向进化以任何理想的方式改变和控制。我们将证明，光系统的功能可以优化到任何特定条件下给定一组适当的选择压力。我们将为光系统化学的控制和优化提供工具和分子蓝图，以实现潜在的未来分子应用。