Rewiring photosynthetic pathways in a purple bacterium (CLARKE_U27DTP)
There is an increasing need for biological solutions to challenges such as metal recovery and detoxification of organic compounds from industrial waste. Many microorganisms have been engineered to allow these processes to occur, but they typically require additional chemical substrates for energy to maintain the cell culture. Photosynthesis is a potential alternative energy source but rewiring metabolic pathways to use the energy of sunlight is often challenging.
The purple phototrophic bacteria Rhodopseudomonas palustris is a versatile organism that can switch between light driven iron oxidation and dimethylsulfoxide (DMSO) respiration in the absence of light. In principle, expression of these two pathways at the same time should allow for light driven iron and DMSO reduction, bypassing central metabolism. This project aims to deliver on this proof of principle, by engineering R. palustris and characterising the energetics of engineered reaction pathway both in vitro and in vivo. Molecular biology will be used to assemble plasmids for the expression of both pathways under phototrophic conditions. The novel PioAB complex iron oxidising complex will be extracted from R. palustris and characterised by Cryo-EM, while spectroscopy and spectrophotometry will be used to study electron transfer between the different component proteins. Once the pathway is confirmed in vitro, the ability of engineered R. palustris to oxidise both iron and reduce DMSO will be explored.
Once this engineered strain has established as a proof-of-concept, there will be the opportunity to adapt the pathways to utilise other metals and more industrially relevant organic materials, depending on the interests of the student.
Cyanobacterial redox carriers support photosynthesis in a purple phototrophic bacterium.
Bowie AGM, Hitchcock A, Proctor MS, Martin EC, Swainsbury DJK, Hunter CN.
Biochem J. 2025 13:1123-44. doi: 10.1042/BCJ20253114.
Burton JAJ, Edwards MJ, Richardson DJ, Clarke TA
Electron Transport Across Bacterial Cell Envelopes. (2025)
Annu Rev Biochem. 94(1):89-109. doi: 10.1146/annurev-biochem-052621-092202.