The discovery of how a critical enzyme “hidden in nature’s blueprint” works sheds new light on how cells control key processes in carbon fixation, a process fundamental to life on Earth. A discovery by scientists from the Australian National University (ANU) and the University of Newcastle (UoN) could help create climate-resilient crops that can absorb carbon dioxide from the atmosphere more efficiently, helping to produce more food in the process.

A published study Science DevelopmentsIt demonstrates a previously unknown function of an enzyme called carboxysomal carbonic anhydrase (CsoSCA), found in cyanobacteria, also called blue-green algae, to maximize the ability of microorganisms to remove carbon dioxide from the atmosphere.

Cyanobacteria are widely known for their toxic proliferation in lakes and rivers. But these little blue-green insects are quite common and live in the world’s oceans as well.

Although they can pose a danger to the environment, researchers describe them as “tiny carbon superheroes.” They play an important role in sequestering approximately 12% of the world’s carbon dioxide each year through the process of photosynthesis.

First author and Ph.D. ANU researcher Sasha Pulsford explains how effective these microorganisms are at sequestering carbon.

“Unlike plants, cyanobacteria have a system called the carbon concentrating mechanism (CCM) that allows them to fix carbon from the atmosphere and convert it into sugar at a much higher rate than standard plant and crop species,” Ms Pulsford said. said.

At the center of the SCC are large protein compartments called carboxysomes. These structures are responsible for absorbing carbon dioxide, housing CsoSCA and another enzyme called Rubisco. CsoSCA and Rubisco enzymes work in harmony, demonstrating the highly efficient nature of CCM. CsoSCA functions to create a high local concentration of carbon dioxide within the carboxysome; Rubisco can then take this and convert it into sugar for consumption by the cell.

Lead author Dr Ben Long, from UoN, said: “Until now scientists were unsure how the CsoSCA enzyme was controlled. Our research focused specifically on unraveling this mystery in a large group of cyanobacteria found around the world. What we found was completely unexpected.

“The CsoSCA enzyme dances to the tune of another molecule called RuBP, which activates it like a switch. Think of photosynthesis like making a sandwich. The carbon dioxide in the air is the filler, but the photosynthetic cell needs to provide the bread. Just like you need the bread to make the sandwich, RuBP is ; the rate at which carbon dioxide is converted to sugar depends on how quickly the RuBP is served.

“How fast the CsoSCA enzyme delivers carbon dioxide to Rubisco depends on the amount of RuBP. When there is a sufficient amount, the enzyme is activated. However, if the cell runs out of RuBP, the enzyme shuts down, allowing the system to be fine-tuned. And surprisingly, the CsoSCA enzyme has been included in nature’s plan from the beginning and is waiting to be discovered.” .”

Designing crops that capture and use carbon dioxide more efficiently would provide a major boost to the agricultural industry, greatly increasing yields while reducing demand for nitrogen fertilizers and irrigation systems, scientists say. It will also make the world’s food systems more resilient to climate change.

Ms Pulsford said: “Understanding how CCM works will not only enrich our knowledge of the natural processes fundamental to the Earth’s biogeochemistry, but can also help us create sustainable solutions to some of the biggest environmental challenges the world faces.”