Lumazine synthase

Lumazine synthase is an enzyme with systematic name 5-amino-6-uracil butanedionetransferase. This enzyme catalyses the following chemical reaction
This reaction is part of the biosynthesis of riboflavin. Lumazine synthase is thus found in those organisms which produce riboflavin.
Depending on the species, 5, 10 or 60 copies of the enzyme bind together to form homomers. In the case of 60 copies, the enzyme units form a icosahedral hollow cage. In some bacteria, this cage contains another enzyme involved in the riboflavin synthesis, riboflavin synthase.
These icosahedral cages have been investigated for use in drug delivery or as vaccines, delivering antigens. Using directed evolution, Lumazine synthase has been modified so that it forms larger cages that preferentially package RNA molecules that code for the protein, akin to a virus capsid.