An international research consortium, led by Dr. Hab. Yusuke Azuma from the Malopolska Centre of Biotechnology at Jagiellonian University has uncovered how bacteria package enzymes into nanoscale “cages” for efficient vitamin B2 production. The findings, published in Nature Communications, reveal an elegant mechanism underlying this highly specialized biochemical system.
A molecular cage for vitamin B2 production
At the heart of the discovery lies an enzyme-based “cage” in which vitamin B2 (riboflavin) is produced. While humans and animals must obtain this nutrient from food such as mushrooms, which are particularly rich in vitamin B2, other organisms can synthesize it themselves. The enzyme packaging mechanisms into a protein cage is not widespread and is found only in certain bacteria, making it especially intriguing from evolutionary perspectives. Unlike eukaryotic cells, bacteria lack membrane-bound organelles, which is probably why they use proteins for compartmentalization of biochemical processes. Such spatial organization of enzymes provides a means for efficient vitamin biosynthesis within complex cellular environments.
Breakthrough discovery: rare “open” cage
The vitamin B2 biosynthesis compartment was first identified in a soil bacterium in the 1980s. An enzyme, lumazine synthase, forms a hollow cage-like structure that encapsulates another enzyme riboflavin synthase. Since then, scientists have struggled to observe how they are formed. Standard approaches such as X-ray crystallography all failed.
– “For years, we knew this system existed, but we did not understand how it worked. It was like looking at a closed cage without a key to open it,” says the leading author Dr. Łukasz Koziej from MCB.
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Image: Illustrative photo of forest mushrooms
Credit: Arkadiusz Dobosz