Photosynthetic water oxidation driven by near infra-red light

近红外光驱动的光合水氧化

• 批准号: BB/R001383/1
• 负责人: Alfred Rutherford
• 金额: $ 57.73万
• 依托单位: Imperial College London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2017
• 资助国家: 英国
• 起止时间: 2017 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FR001383%2F1
• 关键词: Photosynthetic; water; oxidation; driven; near

Photosynthesis is the process that converts solar energy into the chemical energy that powers life. The light is used to split water, removing some of its electrons and using them to pull down carbon dioxide from the atmosphere to make the building blocks and fuel for life. When water is split in this way, protons (hydrogen ions) and oxygen are released. The oxygen accumulates in the atmosphere, reacting with UV to form the protective ozone layer. The oxygen also provides a reactive environment that allows respiration to occur. Both of these roles of oxygen were crucial for the development of multicellular organisms: life as we know it.The most important photosynthetic enzyme is photosystem II (PSII), the water splitting enzyme. It is the enzyme that changed the planet. Water is very unreactive and splitting it is hard to do. An enzyme capable of splitting water seems to have evolved only once and all O2-producing photosynthesizers, from the most ancient cyanobacterium to the oak tree, use the same enzyme.Such difficult chemistry requires a lot of energy and this comes from sunlight. The amount of energy in light depends on its colour and PSII uses red light absorbed by a pigment called chlorophyll a. Until recently it was thought that all PSIIs have chlorophyll a at the heart of the process. There have been decades of discussion about why red light (680nm) is the lowest energy needed to perform water oxidation: this is known as the red-limit.The red limit was questioned when it was found that a marine bacterium, which was shaded by a green sea-squirt (!), had chlorophyll d performing the photochemistry at around 710nm. An even longer wavelength pigment, chlorophyll f, was discovered recently. This time it was not just a quirky one-off in a weird ecological niche, chlorophyll f was found to be present in a wide range of common cyanobacteria. However the chlorophyll f is only made when they grow in near-darkness, shaded from visible light but exposed to far-red/near-IR light, e.g. deep in bacterial mats in hot springs, or in some rocks. The role of chlorophyll f is generally considered to be only for gathering light but not for the photochemical part of photosynthesis. We have now found that the chlorophyll f does seem to perform photochemistry in PSII. This surprising result represents a major extension of the red limit.These strange far-red PSIIs perform normal PSII chemistry and yet they are quite different from normal PSII in energy terms. In the present project we intend to study this new world of long-wavelength photosynthesis, to follow up our surprising discovery, to understand how it works, to assess what changes have occurred that allow PSII to function with less energy, and to see if the move to lower energy gives better energy efficiency. Since it seems unlikely that there is such a thing as a free lunch, we shall also test if the improved energy efficiency comes with penalties in terms of it resilience to variations in light intensity, for example. This project will involve studying PSII in living cells, membranes and in the isolated enzyme using a range of biochemical and biophysical methods.This demonstration of oxygenic photosynthesis working well beyond the established red limit, takes us into a realm of the subject that is largely unstudied; and yet longer wavelength photosynthesis is already a high profile engineering target aimed at making crops and bioenergy more efficient. Normal photosynthesis is inefficient and much effort goes into thinking up ways of improving it. Engineering longer wavelength photosynthesis seemed a far-off pipedream but now it turns out that nature has already done the engineering. Our aim here is to determine if moving to far-red photosynthesis will provide a useful technological target with an improved energy budget and to test if it comes with a loss of resilience that could restrict the use of engineered long-wavelength photosynthesis to specific growth conditions.

光合作用是将太阳能转化为生命所需的化学能的过程。光被用来分解水，去除其中的一些电子，并利用它们从大气中吸收二氧化碳，以制造生命的基石和燃料。当水以这种方式分裂时，质子（氢离子）和氧气被释放出来。氧气在大气中积累，与紫外线反应形成保护臭氧层。氧气还提供了允许呼吸发生的反应环境。氧的这两个作用对多细胞生物的发展至关重要：我们所知道的生命。最重要的光合酶是光系统II（PSII），水分解酶。它是改变地球的酶。水是非常不活泼和分裂它是很难做到的。一种能够分解水的酶似乎只进化了一次，而所有产生氧气的光合作用生物，从最古老的蓝藻到橡树，都使用相同的酶。这种复杂的化学反应需要大量的能量，而这些能量来自阳光。光的能量取决于它的颜色，PSII利用被称为叶绿素a的色素吸收的红光。直到最近，人们还认为所有PSII都在这个过程的核心中含有叶绿素a。关于为什么红光（680 nm）是进行水氧化所需的最低能量的讨论已经持续了几十年：这被称为红限。当发现一种海洋细菌被绿色海鞘（！）遮蔽时，红限受到质疑，叶绿素d在710 nm左右进行光化学反应。最近发现了一种波长更长的色素，叶绿素f。这一次，它不仅仅是一个奇怪的生态位中的一个古怪的一次性事件，叶绿素f被发现存在于广泛的常见蓝藻中。然而，叶绿素f只有在接近黑暗的环境中生长，远离可见光，但暴露在远红光/近红外光下，例如在温泉中的细菌垫深处，或在一些岩石中。叶绿素f的作用通常被认为只是聚集光，而不是光合作用的光化学部分。我们现在已经发现，叶绿素f似乎在PSII中执行光化学。这个令人惊讶的结果代表了红限的一个主要延伸。这些奇怪的远红PSII执行正常的PSII化学，但它们在能量方面与正常的PSII有很大的不同。在本项目中，我们打算研究这个长波长光合作用的新世界，跟进我们令人惊讶的发现，了解它是如何工作的，评估发生了什么变化，使PSII能够以更少的能量发挥作用，并看看向低能量的转变是否会带来更好的能源效率。由于似乎不太可能有免费的午餐，我们还将测试提高能源效率是否会带来对光照强度变化的适应性方面的惩罚。该项目将涉及使用一系列生物化学和生物物理学方法研究活细胞、膜和分离酶中的PSII。这一氧光合作用的演示远远超出了既定的红色极限，将我们带入了一个基本上未被研究的主题领域;然而，更长波长的光合作用已经是一个备受瞩目的工程目标，旨在使作物和生物能源更有效。正常的光合作用效率很低，人们花了很多精力去想办法改进它。设计更长波长的光合作用似乎是一个遥远的梦想，但现在事实证明，大自然已经完成了这项工程。我们的目标是确定转向远红外光合作用是否会提供一个有用的技术目标，改善能量预算，并测试它是否会失去弹性，从而限制工程长波长光合作用在特定生长条件下的使用。

项目成果

Absorption changes in Photosystem II in the Soret band region upon the formation of the chlorophyll cation radical [PD1PD2].

叶绿素阳离子自由基 [PD1PD2] 形成后，Soret 带区域中光系统 II 的吸收变化。

• DOI: 10.1007/s11120-023-01049-3
• 发表时间: 2023
• 期刊: Photosynthesis research
• 影响因子: 3.7
• 作者: Boussac A

Global distribution of a chlorophyll f cyanobacterial marker.

• DOI: 10.1038/s41396-020-0670-y
• 发表时间: 2020-09
• 期刊: The ISME journal
• 作者: Antonaru LA;Cardona T;Larkum AWD;Nürnberg DJ
• 通讯作者: Nürnberg DJ

Absorption changes in Photosystem II in the Soret band region upon the formation of the chlorophyll cation radical (PD1PD2)+

叶绿素阳离子自由基 (PD1PD2) 形成后索雷带区域中光系统 II 的吸收变化

• DOI: 10.21203/rs.3.rs-3165700/v2
• 发表时间: 2023
• 作者: Boussac A

Changes in supramolecular organization of cyanobacterial thylakoid membrane complexes in response to far-red light photoacclimation.

• DOI: 10.1126/sciadv.abj4437
• 发表时间: 2022-02-11
• 期刊: Science advances
• 影响因子: 13.6
• 作者: MacGregor-Chatwin C;Nürnberg DJ;Jackson PJ;Vasilev C;Hitchcock A;Ho MY;Shen G;Gisriel CJ;Wood WHJ;Mahbub M;Selinger VM;Johnson MP;Dickman MJ;Rutherford AW;Bryant DA;Hunter CN
• 通讯作者: Hunter CN

Absorption changes in Photosystem II in the Soret band region upon the formation of the chlorophyll cation radical [P D1 P D2 ] +

叶绿素阳离子自由基形成后索雷带区域光系统 II 的吸收变化 [P D1 P D2 ]

• DOI: 10.1101/2022.05.12.491653
• 发表时间: 2022
• 作者: Boussac A