University of Sheffield. November 13,
2019 -- Scientists have solved the structure of one of the key components of
photosynthesis, a discovery that could lead to photosynthesis being
'redesigned' to achieve higher yields and meet urgent food security needs.
The study, led by the University of
Sheffield and published today 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, the team 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.
Lorna Malone, the first author of the
study and a PhD student 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, reader in Biochemistry
at the University of Sheffield and one of the supervisors of the study 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.
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.
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