A team of chemists at the Massachusetts Institute of Technology has achieved a major breakthrough in the study of Rubisco, the key enzyme in photosynthesis. Using directed evolution techniques, they successfully increased the catalytic efficiency of Rubisco from bacteria in low-oxygen environments by up to 25%, offering new hope for improving crop photosynthesis rates and agricultural yields.
Rubisco plays a central role in photosynthesis by incorporating carbon dioxide into organic compounds to produce sugars. However, this most abundant enzyme on Earth has long been criticized for its low efficiency. MIT researchers employed a novel mutagenesis technique called MutaT7 to accelerate the directed evolution of Rubisco in living cells, significantly improving screening efficiency.
The research team started with a highly active Rubisco enzyme isolated from the semi-anaerobic bacterium Gallionellaceae. Through six rounds of directed evolution experiments, they successfully identified three mutants. These mutations significantly enhanced the enzyme's resistance to oxygen, enabling it to preferentially react with carbon dioxide in oxygen-rich environments and substantially improving carboxylation efficiency. Experimental data showed that the optimized enzyme increased catalytic efficiency by 25% under low-oxygen conditions.
Senior author of the study and MIT Professor of Chemistry Matthew Shoulders stated: "This result provides compelling proof for improving Rubisco properties. We are now applying the technology to plant forms of Rubisco, with the hope of reducing energy losses caused by photorespiration." It is estimated that photorespiration in plants consumes about 30% of the absorbed solar energy, and the optimized enzyme can effectively reduce this loss.
Lead author Julie McDonald noted that the new continuous directed evolution technique overcomes the limitations of traditional methods, allowing observation of a greater variety of enzyme mutation combinations. Compared to traditional error-prone PCR techniques, MutaT7 enables efficient mutation and screening of target genes, significantly shortening the research cycle.
Currently, the research team has initiated follow-up studies to apply this technology to plant Rubisco. Robert Wilson, a researcher in the Department of Chemistry, emphasized: "This breakthrough opens a new path for increasing agricultural productivity. By improving the core enzyme of photosynthesis, we hope to cultivate higher-yielding and more efficient crop varieties."
The research results were published in the Proceedings of the National Academy of Sciences, marking an important advancement in the application of protein engineering technology in agriculture and providing innovative solutions to address global food security challenges.
