Tuning near-infrared photosynthesis

光合作用是我们吃的所有食物的来源，也是我们使用的几乎所有能量的来源。这个过程利用阳光从大气中去除二氧化碳，并将其转化为糖，为地球提供养分。阳光被叶绿素色素捕获，叶绿素色素由蛋白质排列并保持在适当的位置；这些色素蛋白的排列被称为天线复合体。天线收集光能，并将其输送到专门的“反应中心”，在那里能量被转换成一种可供电池使用的形式。植物和蓝藻（蓝绿藻）利用叶绿素（Chl）色素捕捉可见光（400-700纳米）来进行“含氧”光合作用，释放支持呼吸的氧气。此外，各种各样的细菌也能够利用远红光和近红外光（约700纳米）来进行“无氧”光合作用，这些光我们看不见，但能感觉到是热。这种模式的光合作用依赖于细菌叶绿素（BChl）色素，而不是chl。大多数无氧光合作用体使用BChl a收集750-900 nm之间的光，而少数使用BChl b收集非常低能量波长bb0 - 1000 nm。900-1000纳米之间的大部分光被大气中的水吸收，因此很少被自然产生的光养生物利用。该项目将揭示含BChl b的生物如何能够将吸收范围扩大到这个很少使用的区域，以及是否有可能获得更低的能量波长来为光合作用提供动力。我们将通过创建新版本的BChl b天线反应中心复合体来实现这一目标，该复合体能够捕捉近红外的独特范围。我们还将测量这些复合物中色素的紧密程度，以及能量收集和输送到反应中心为细胞供电的速度和效率。实现这些目标将揭示如何控制和调整光谱近红外区域的吸收，并看看光合作用的低能量限制是否可以被超越，长期目标是有效地捕获太阳光谱的整个可用范围，以可持续的方式解决一些人类即将面临的燃料和食物供应挑战。

Photosynthesis is the source of all the food we eat, and almost all of the energy we use. This process uses sunlight to remove carbon dioxide from the atmosphere and converts it into sugars that feed the planet. Sunlight is captured by chlorophyll pigments that are arranged and held in place by proteins; these pigment-protein arrangements are known as antenna complexes. Antennas collect the light energy and funnel it towards specialised 'reaction centres', where the energy is converted to a form that can be used by the cell.Plants and cyanobacteria (blue-green algae) use chlorophyll (Chl) pigments to capture visible light (400-700 nm) to perform 'oxygenic' photosynthesis, releasing the oxygen that supports respiration. Additionally, a diverse range of bacteria are also capable of using far-red and near-infrared light (>700 nm), which we cannot see but feel as heat, to perform 'anoxygenic' photosynthesis. This mode of photosynthesis relies on the bacteriochlorophyll (BChl) pigments, rather than Chls.The majority of anoxygenic photosynthesisers use BChl a to harvest light between 750-900 nm, while a few use BChl b and harvest very low energy wavelengths >1000 nm. Most of the light between 900-1000 nm is absorbed by water in the atmosphere, so it is rarely used by naturally-occurring phototrophs. This project will reveal how BChl b-containing organisms are able to extend absorption past this rarely-used region, and whether it is possible to access even lower energy wavelengths to power photosynthesis. We will do this by creating new versions of the BChl b antenna-reaction centre complex able to capture unique ranges in the near-infrared. We will also measure how close together the pigments in these complexes are, and how quickly/efficiently energy can collected and funnelled to the reaction centre to power the cell.Achieving these aims will reveal how to control and tune absorption in the near-infrared region of the spectrum, and to see if the low-energy limit for photosynthesis can be surpassed, with the long-term goal of efficiently capturing the entire usable range of the solar spectrum to tackle some of humanity's impending fuel and food supply challenges in a sustainable manner.