Australian National University and Sydney University researchers are revolutionising agricultural science. In doing so, they are creating a unique method to improve photosynthesis in crops. This pivotal research seeks to maximize the efficiency of Rubisco. This enzyme is responsible for the initial energetic state of fixing carbon dioxide in photosynthesis. Despite its importance, Rubisco is notoriously inefficient, often reacting with oxygen instead of carbon dioxide, resulting in a wasteful process that hampers plant growth.
To better filter Rubisco and speed up its function, the research team designed nanoscale “offices,” called encapsulins, to localize the protein in a specialized space. This cutting-edge strategy goes right to the heart of Rubisco’s inefficiencies. A national private-sector initiative, it seeks to cut red tape, enable higher-value crop production and more. The researchers are now one step closer to genetically engineering improved photosynthesis into important food crops. So, they engineered these encapsulins done one single gene is needed to build them.
The Challenge of Rubisco Efficiency
Yet Rubisco, one of the most abundant enzymes on Earth, is remarkably unique and inefficiency usually isn’t a bragging point in biology. It is inefficient and can unintentionally start a reaction with oxygen, which results in an avoidable process that wastes energy and materials. This inefficiency has led important food crops such as wheat, rice, canola, and potatoes to produce Rubisco in large quantities as a brute-force solution.
“Rubisco is very slow and can mistakenly react with oxygen instead of CO2 which triggers a whole other process that wastes energy and resources. This mistake is so common that important food crops such as wheat, rice, canola and potatoes have evolved a brute-force solution: mass-produce Rubisco,” – Davin Wijaya
Plant leaves have a very high concentration of Rubisco and it can account greater than 50% of the soluble protein within. This powerful presence requires substantial energy and nitrogen from the plants. To resolve this inefficiency, researchers have already made great strides to install natural CO 2 -concentrating systems into crops. These systems are not without their own complexities.
Innovation with Encapsulins
The encapsulins engineered by the research team are a potentially modular answer to Rubisco conundrum. Unlike carboxysomes—natural compartments that house Rubisco and require multiple genes to assemble—encapsulins can package any type of Rubisco due to their simpler structure. This flexibility in design makes plant integration much easier and more cost-effective to implement into any type of plant’s system.
“Another cool advantage of our system is that it’s modular. Carboxysomes can only package their own Rubisco, whereas our encapsulin system can package any type,” – Dr. Taylor Szyszka
They did this by appending a short “address tag” of 14 amino acids. This tag sends Rubisco to its rightful home within the encapsulins in the assembly line. This level of precision just raises the probability of them going together, working correctly.
“Most excitingly we found the pores in the encapsulin shell allow for the entry and exit of Rubisco’s substrate and products,” – Dr. Taylor Szyszka
The modular nature of this encapsulin system gives researchers the ability to tailor its compatibility. They can customize it for wide-ranging use cases across multiple crops.
Future Directions for Crop Improvement
And so far, preliminary results are painting a positive picture! Moving forward, researchers are focusing on the next steps to roll out this technology across US agriculture. The encapsulin system has increased promise beyond extending the reach of the photosynthetic microbiome to boosting overall plant productivity.
“We know we can produce encapsulins in bacteria or yeast; making them in plants is the next sensible step. Our preliminary results look promising,” – Davin Wijaya
The ramifications of this study reach way farther than just making rice grow more. By maximizing the efficiency of photosynthesis using innovative engineering approaches, researchers hope to play a role in global food security and sustainability efforts. This new work at the Australian National University and the University of Sydney is an important step forward. We need their technical expertise to figure out and replenish one of the most fragile yet essential, life-giving processes on Earth.