Quality control in synthetic photosynthesis validates the mimicry of natural light
Humans can do many impressive things, but plants have a unique ability: they convert sunlight directly into energy through photosynthesis. Recent research now suggests that scientists are narrowing the gap in artificially replicating this process.
Researchers from Osaka Metropolitan University have successfully mapped the 3D structure of an artificial photosynthetic antenna protein complex called light-harvesting complex II (LHCII) and demonstrated that this synthetic LHCII closely mimics its natural equivalent. This breakthrough significantly advances the understanding of how plants capture and direct solar energy, marking an essential step toward advances in artificial photosynthesis.
Led by Associate Professor Ritsuko Fujii and former graduate student Soichiro Seki of the Graduate School of Science and Research Center for Artificial Photosynthesis, the research has been published in PNAS Nexus.
Photosynthesis, the process of converting sunlight into usable energy, involves numerous complex interactions between different molecules and proteins. LHCII is one of the most crucial components: a pigment-protein complex found in chloroplasts of plants and algae that plays an important role in capturing sunlight and channeling energy for photosynthesis. LHCII consists of a complex array of proteins and pigments and is a challenging structure to reproduce outside natural systems.
Several previous attempts aimed at replicating LHCII have raised the question: do these artificial constructs come close to nature’s original design?
“Traditional methods fall short in determining the exact structure of in vitro reconstituted LHCII,” said Dr. Seki.
In vitro reconstitution, a laboratory technique, allows scientists to recreate LHCII outside plants by synthesizing its protein portion in *E. coli* and combines it with natural pigments and lipids.
Using advanced cryo-electron microscopy, the research team analyzed the 3D structure of the artificially reconstituted LHCII. This technique, which was awarded the Nobel Prize in Chemistry in 2017, involves freezing samples at extremely low temperatures to capture highly detailed images. Through this method, the team gained an in-depth understanding of how pigments and proteins are located within the synthetic complex.
“Our results showed that the laboratory-made LHCII was virtually identical to the natural version, with only a few minor differences,” said Dr. Seki.
These findings confirm the efficacy of the in vitro reconstitution technique and open doors for further research into the functional role of LHCII in photosynthesis. The research forms the basis for innovations in the field of artificial photosynthesis and plant production technologies.
“Our result not only provides a structural basis for the reconstituted LHCII, but also evaluates the functions based on the structure of the reconstituted LHCII,” Professor Fujii added. “We hope this will facilitate further research into the molecular mechanisms by which plants use sunlight for chemical reactions.”
Research report:Structure-based validation of recombinant light-harvesting complex II
