Scientists unlock key to photosynthesis

Scientists from Yorkshire have solved the structure of one of the key components of photosynthesis.

This discovery could lead to photosynthesis being ‘redesigned’ to achieve higher yields and meet urgent food security needs.

The research, published on 13 November in the journal Nature, reveals the structure of cytochrome b6f - the protein complex that significantly influences plant growth via photosynthesis.

Photosynthesis is the foundation of life on Earth providing the food, oxygen, and energy that sustains the biosphere and human civilisation.

Using a high-resolution structural model, scientists found that the protein complex provides the electrical connection between the two light-powered chlorophyll-proteins (Photosystems I and II) found in the plant cell chloroplast that convert sunlight into chemical energy.

The research was carried out by a collaboration of scientists from the University of Sheffield and the University of Leeds.

Co-author Professor Neil Ranson, from the University of Leeds’ Astbury Centre and School of Molecular and Cellular Biology, said: “This beautiful structure was made possible by Leeds’ state-of-the-art microscopes allowing us to ‘see’ biological material at near-atomic detail.

“We’re delighted to be able to collaborate with the best scientists, not just from across the North of England but from around the world, who understandably are coming to us to access this cutting-edge technology.”

Lorna Malone, the first author of the study and a PhD researcher in the University of Sheffield’s Department of Molecular Biology and Biotechnology, said: “Our study provides important new insights into how cytochrome b6f utilises the electrical current passing through it to power up a ‘proton battery’. This stored energy can then be then used to make ATP, the energy currency of living cells. Ultimately this reaction provides the energy that plants need to turn carbon dioxide into the carbohydrates and biomass that sustain the global food chain.”

The high-resolution structural model, determined using single-particle cryo-electron microscopy, reveals new details of the additional role of cytochrome b6f as a sensor to tune photosynthetic efficiency in response to ever-changing environmental conditions. This response mechanism protects the plant from damage during exposure to harsh conditions such as drought or excess light.

Dr Matt Johnson, one of the supervisors of the study from the University of Sheffield, added: 

“Cytochrome b6f is the beating heart of photosynthesis which plays a crucial role in regulating photosynthetic efficiency.

“Previous studies have shown that by manipulating the levels of this complex we can grow bigger and better plants. With the new insights, we have obtained from our structure we can hope to rationally redesign photosynthesis in crop plants to achieve the higher yields we urgently need to sustain a projected global population of 9-10 billion by 2050.”

The research was conducted in collaboration with the Astbury Centre for Structural Molecular Biology at the University of Leeds, using their cryo-electron microscope facilities.

Researchers now aim to establish how cytochrome b6f is controlled by a myriad of regulatory proteins and how these regulators affect the function of this complex.

Further information

Top image shows a cryo-electron microscope model of cytochrome b6f, a protein complex found in plant chloroplasts.

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