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Lumazine synthase (, ''6,7-dimethyl-8-ribityllumazine synthase'', ''6,7-dimethyl-8-ribityllumazine synthase 2'', ''6,7-dimethyl-8-ribityllumazine synthase 1'', ''lumazine synthase 2'', ''lumazine synthase 1'', ''type I lumazine synthase'', ''type II lumazine synthase'', ''RIB4'', ''MJ0303'', ''RibH'', ''Pbls'', ''MbtLS'', ''RibH1 protein'', ''RibH2 protein'', ''RibH1'', ''RibH2'') is an enzyme with systematic name ''5-amino-6-(D-ribitylamino)uracil butanedionetransferase''. This enzyme catalyses the following chemical reaction
: 1-deoxy-L-glycero-tetrulose 4-phosphate + 5-amino-6-(D-ribitylamino)uracil 6,7-dimethyl-8-(D-ribityl)lumazine + 2 H2O + phosphate
:
This reaction is part of the biosynthesis of
This reaction is part of the biosynthesis of riboflavin
Riboflavin, also known as vitamin B2, is a vitamin found in food and sold as a dietary supplement. It is essential to the formation of two major coenzymes, flavin mononucleotide and flavin adenine dinucleotide. These coenzymes are involved in ...
(vitamin B2). Lumazine synthase is thus found in those organisms (plants, fungi and most microorganisms) 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
In immunology, an antigen (Ag) is a molecule or molecular structure or any foreign particulate matter or a pollen grain that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune response. ...
. Using directed evolution, Lumazine synthase has been modified so that it forms larger cages that preferentially package RNA
Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. RNA and deoxyribonucleic acid ( DNA) are nucleic acids. Along with lipids, proteins, and carbohydra ...
molecules that code for the protein, akin to a virus capsid.
References
External links
* {{Portal bar, Biology, border=no EC 2.5.1