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，为地球提供食物。阳光被叶绿素色素捕获，叶绿素色素被蛋白质排列和固定在适当的位置;这些色素-蛋白质排列被称为天线复合物。植物和蓝藻利用叶绿素（Chl）色素捕捉可见光（400-700 nm）进行光合作用，释放氧气支持呼吸作用。植物和蓝藻利用叶绿素（Chl）色素捕捉可见光（400-700 nm）进行光合作用，释放氧气支持呼吸作用。此外，各种各样的细菌也能够使用远红光和近红外光（>700 nm），我们看不到，但感觉到热，进行“无氧”光合作用。这种光合作用模式依赖于细菌叶绿素（BChl）色素，而不是Chls。大多数无氧光合作用使用BChl a来收获750-900 nm之间的光，而少数使用BChl B并收获>1000 nm的非常低的能量波长。大部分900-1000 nm之间的光被大气中的水吸收，因此它很少被自然产生的光养生物使用。该项目将揭示含BChl b的生物如何能够将吸收扩展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。我们将通过创造新版本的BChl B天线反应中心复合物来实现这一目标，该复合物能够捕获近红外线的独特范围。我们还将测量这些复合物中的色素之间的距离，以及能量如何快速/有效地收集并输送到反应中心为细胞提供动力。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，并了解光合作用的低能极限是否可以被超越，其长期目标是有效地捕获整个可用范围的太阳光谱，以可持续的方式解决人类即将面临的一些燃料和粮食供应挑战。

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.