Engineering Semi-Artificial Cells for New-to-Nature Photosynthesis

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Photosynthesis is an ancient process carried out by organisms including plants, algae and cyanobacteria, whereby sunlight is captured and converted to energy vectors that are then used to synthesis chemicals. However, natural photosynthetic processes were not evolved for efficiency. The ability to engineer more efficient and enhanced photosynthetic processes would lead to more promising sustainable ways of clean (bio)energy generation.This project aims to build semi-artificial photosynthetic cells from the bottom up using a new biohybrid approach, to ultimately demonstrate how to engineer cells for enhanced or new-to-nature photosynthesis. The objectives towards this are to firstly isolate and modify the light harvesting/charge propagating component of photosynthesis (the thylakoids) to be able to convert more of the solar spectrum into usable energy/charge carriers. The second objective is to completely reprogram powerful CO2 concentrating capsules found in cyanobacteria, called carboxysomes, by replacing the naturally slow enzyme for CO2 conversion (RUBISCO) with much more efficient enzymes that can turn protons and CO2 into useful feedstocks including hydrogen gas and formate. The last objective is to encapsulate the two new biohybrid components into artificial cells so that the new 'light reaction' can be in close enough proximity to drive the new 'dark reactions'. This strategy will allow us to understand how to best tune the ratios of 'light' to 'dark' components within photosynthesis, as well as any intermediate energy carriers, to best balance the input and output fluxes and give rise to the most efficient light-to-chemical conversion systems. This is a highly original approach for engineering photosynthetic cells that will likely yield new photosynthetic efficiencies or chemistries not possible using classical synthetic biology approaches. This work will provide valuable lessons into how photosynthetic cells can be bioengineered for bespoke performances in the future, which will benefit severl research areas beyond clean energy, including agriculture and bio-manufacturing.