Chlorophyll-f-containing Photosystem I

在2018年，我们发现了一种新型的光合作用，它利用吸收红外光的叶绿素f进行光化学反应。光合作用利用阳光为地球上的生命提供能量，并将氧气送入大气。自其出现以来，光合作用产生的氧气形成了臭氧层，屏蔽了致命的紫外线，并允许呼吸发生，导致复杂生命的进化。光合作用还从大气中吸收了大部分二氧化碳，并将其转化为生物物质，从而使地球上的环境适合目前的居民。鉴于光合作用的重要性，一种新的光合作用的发现确实引起了轰动。在一些进行正常可见光光合作用的细菌中发现了这种新的过程。然而，当这些细菌发现自己处于黑暗中，被其他使用可见光但不使用红外线的光合生物遮蔽时，它们能够打开一套特殊的基因来制造新的光合酶，这些酶与红外线一起工作。我们发现，叶绿素f在这种类型的光合作用的核心进行关键的光驱动化学反应。这一发现是一个惊喜，因为标准类型的光合作用在所有广泛的光合物种中几乎没有或根本没有变化，从蓝藻到橡树。人们一直认为，叶绿素a吸收的可见光能量仅足以完成要求苛刻的化学反应。因此，发现低能量，长波长的光可以用来做完全相同的过程，这是非常出乎意料的。光合作用在能量方面效率低下，这也使得农业效率低下。这就是为什么我们投入大量的能源，以化肥，杀虫剂和工艺的形式，以获得我们需要的产量。毫不奇怪，多年来科学家们一直在研究改善光合作用的方法。最近有显着的进展，其中通过修改优化光利用和保护植物在变化的光条件下的调节过程来获得增加的作物产量。作物的一个主要的内在效率低下是下层树冠的叶子被上层树冠的叶子遮住了光线。新的红外光合作用原理上可以引入作物，在需要时在荫蔽的叶子中发挥作用。这可以显著增加光合产量。将光合作用的光谱扩展到更长的波长已经讨论了很多年，但这似乎是一个相当不现实的任务。发现进化已经做到了这一点，使整个想法更加可行。目前的项目涉及的研究是需要了解进化做了什么，以使系统以更少的能量工作。通过将新系统与标准系统进行比较，我们已经在这一领域取得了快速进展，但目前的项目是第一个专门处理红外驱动的光系统I的项目，该酶提供将二氧化碳固定到生物体中所需的能量。要做到这一点，我们将准确地确定哪些酶的叶绿素是叶绿素f，以及它们是如何被蛋白质调整，使他们做的工作。我们将结合联合收割机分子生物学、生物化学和生物物理学来整理出理解它如何工作所需的结构和机械细节。通过这种方式，我们可以提供所需的知识，以确定作物改良的可行性和实施的最佳方法。新的光系统I还提供了一个机会，解开个人叶绿素的贡献。与传统的叶绿素a系统不同，所有（95）色素都是相同的颜色，这些新系统在关键位置有少量不同的叶绿素f。这种做梦也想不到的色谱整理应该可以让古老的谜团得到解决。我们也希望在这个项目中做到这一点。

In 2018 we discovered a new type of photosynthesis that does photochemistry using chlorophyll-f, which absorbs infra-red light. Photosynthesis uses sunlight to provide the energy for life on the planet and put the oxygen into the atmosphere. Since its appearance, the oxygen generated by photosynthesis formed the ozone layer that screens out the deadly UV and allowed respiration to occur, leading to the evolution of complex life. Photosynthesis also pulled down most of the CO2 from the atmosphere and converted it into living matter, resulting in conditions on the planet appropriate for the current inhabitants. Given the importance of photosynthesis, the discovery of a new kind did cause a stir. The new process is found in some bacteria that do normal, visible-light photosynthesis. However, when these bugs find themselves in darkness, shaded by other photosynthetic organisms that use the visible light but not the infra-red, they are able to switch-on a special suite of genes to make new photosynthetic enzymes that works with infra-red light. We showed that chlorophyll-f does the key light-driven chemical reactions at the heart of this type of photosynthesis.This discovery was a surprise as the standard type of photosynthesis shows little or no fundamental variation across all of the wide range of photosynthetic species, from cyanobacteria to oak trees. It had been assumed that the energy of visible light absorbed by chlorophyll-a was only just sufficient to do the demanding chemistry. The discovery that lower energy, longer wavelength light could be used to do exactly the same process, was thus highly unexpected. Photosynthesis is inefficient in energy terms and this makes agriculture inefficient too. This is why we put in enormous quantities of energy, in the form of fertilizers, pesticides, and processes, to get the yields we need. Unsurprisingly, for years scientists have been researching ways of improving photosynthesis. Recently there have been remarkable advances in which increased crop yields were obtained by modifying the regulation processes that optimize light use and protect plants under changing light conditions. A major intrinsic inefficiency in crops is that leaves in the lower canopy are shaded from the light by those in the upper canopy. The new infra-red photosynthesis could in principle be introduced into crops to function when needed in the shaded leaves. This could give a marked increase in photosynthetic yields. Extending the spectrum of photosynthesis to longer wavelengths has been talked about for years but it seemed a rather unrealistic task. The finding that evolution has already done it, makes the whole idea more feasible. The current project involves studies that are needed to learn what evolution has done to get the system to work with less energy. By comparing the new system with the standard one, we have already advanced rapidly in this area, but the present project is the first to deal specifically with the infra-red-driven Photosystem I, the enzyme that provides the energy boost needed to fix CO2 into living matter. To do this we will identify exactly which of the enzyme's chlorophylls are chlorophyll-f and how they are tweaked by the protein to make them do the job. We will combine molecular biology, biochemistry and biophysics to sort out the structural and mechanistic details required to understand how it works. In this way we can provide the knowledge needed to determine the feasibility of crop improvement and the best ways to implement it. The new Photosystem I also provides an opportunity to disentangle the individual chlorophyll contributions. Unlike the conventional chlorophyll-a systems, where all (95) pigments are the same color, these new systems have a small number of distinct chlorophylls-f in key positions. This undreamt-of decluttering of the color spectrum should allow old mysteries to be resolved. We hope to do that too in this project.