Spinach used in neutron studies could unearth secret to stronger plant growth

April 18, 2018 by Elizabeth Rosenthal, Oak Ridge National Laboratory
Uppsala University researcher Marvin Seibert is using neutrons to study RuBisCO, an abundant enzyme essential to life on earth. His team hopes to determine how plants and other organisms use RuBisCO to catalyze a reaction called carbon fixation that converts carbon dioxide into useful organic compounds. Credit: ORNL/Genevieve Martin

Plants, algae, and other organisms produce the RuBisCO enzyme to convert carbon dioxide from the atmosphere into energy-rich molecules, like glucose, that form carbohydrates and other organic carbon compounds essential to life on earth.

This catalytic process is called "." A better understanding of the specific activity involved when RuBisCO kick-starts this chemical reaction could be instrumental to enhancing the enzyme's efficiency and facilitating faster plant growth—a desirable result that could increase crop yields while conserving fertilizer and natural resources.

To this end, researchers from Uppsala University are using neutrons at the Department of Energy's (DOE's) Oak Ridge National Laboratory (ORNL) to determine the protein structure of a RuBisCO sample obtained from spinach leaves.

"We hope to comprehend carbon fixation in atomic-level detail, which would help us figure out exactly what is happening to each carbon dioxide molecule that the enzyme takes out of the atmosphere and brings into the biosphere," said principal investigator Marvin Seibert.

During fixation, organisms "fix" carbon into place by binding it to organic molecules.

Despite playing such a key role in this process, RuBisCO is exceptionally slow and inefficient. To compensate, plants are forced to devote a substantial portion of their valuable resources to producing large quantities of the enzyme.

"A significant amount of the nitrogen that a plant needs for its growth goes into making RuBisCO, which in turn collects the carbon needed for photosynthesis," Seibert said. "Incidentally, a lot of the fertilizer we put in fields ends up in the inner proteins of plants to help contribute to this process."

Because it is produced as a response to the constant demand for carbon, RuBisCO can arguably be categorized as one of the most abundant enzymes on the planet. Scientists estimate that, at some point, every carbon atom in every organism has passed through carbon fixation.

If plants were able to thrive and complete carbon fixation under more efficient conditions, such a cost-saving, environmentally friendly outcome could contribute to overall improvements in the agricultural and economic value of important crops used for food, bio-fuels, and other practical purposes.

Although scientists have used x-ray techniques to study RuBisCO in the past, neutron scattering methods have the distinct advantage of being sensitive to hydrogen. About half of the atoms in biomolecules are hydrogen atoms, which means the ability to pinpoint their location and structure is paramount to characterizing the enzyme's atomic structure.

"If we can produce a neutron crystallography structure where we can see the hydrogen atoms in the RuBisCO active site, we should be able to investigate the enzyme's catalytic mechanism and learn more about the conversion of to organic compounds," Seibert said.

Working with ORNL scientist Flora Meilleur, the Swedish team is pursuing this goal at ORNL's High Flux Isotope Reactor (HFIR) using the IMAGINE instrument, HFIR beamline CG-4-D. They are also running complementary experiments at ORNL's Spallation Neutron Source (SNS) using the MaNDi instrument, SNS beamline 11B.

Previously, the researchers relied on hypotheses and models to examine RuBisCO's catalytic activity, but they anticipate that the neutron scattering research will provide a more concrete foundation on which to build future studies.

"We got results in the first five minutes, and seeing success that quickly is very unusual," Seibert said. "The combination of great instrumentation and wonderful people here makes this experiment possible."

Explore further: Hacking evolution, screening technique may improve most widespread enzyme

More information: John A. Raven. Rubisco: still the most abundant protein of Earth?, New Phytologist (2013). DOI: 10.1111/nph.12197

Related Stories

The future of crop engineering 

December 8, 2017

Photosynthesis is the process underlying all plant growth. Scientists aim to boost photosynthesis to meet the increasing global demand for food by engineering its key enzyme Rubisco. Now, researchers at the Max Planck Institute ...

How algae could save plants from themselves

May 10, 2016

Algae may hold the key to feeding the world's burgeoning population. Don't worry; no one is going to make you eat them. But because they are more efficient than most plants at taking in carbon dioxide from the air, algae ...

This enzyme enabled life to conquer a hostile earth

August 8, 2017

Computers are simulating the ancestral versions of the most common protein on Earth, giving scientists an unparalleled look at early life's development of harnessing energy from the Sun and production of oxygen.

Recommended for you

Sculpting stable structures in pure liquids

February 21, 2019

Oscillating flow and light pulses can be used to create reconfigurable architecture in liquid crystals. Materials scientists can carefully engineer concerted microfluidic flows and localized optothermal fields to achieve ...

Researchers make coldest quantum gas of molecules

February 21, 2019

JILA researchers have made a long-lived, record-cold gas of molecules that follow the wave patterns of quantum mechanics instead of the strictly particle nature of ordinary classical physics. The creation of this gas boosts ...

LMC S154 is a symbiotic recurrent nova, study suggests

February 21, 2019

Astronomers have conducted observations of a symbiotic star in the Large Magellanic Cloud (LMC), known as LMC S154, which provide new insights about the nature of this object. Results of these observations, presented in a ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.