Homologous Superfamily

Lumazine/riboflavin synthase superfamily (IPR036467)

Short name: LS/RS_sf

Overlapping entries


6,7-dimethyl-8-ribityllumazine synthase (lumazine synthase, LS), catalyzes the formation of 6,7-dimethyl-8-ribityllumazine by condensation of 5-amino-6-(D-ribitylamino)uracil with 3,4-dihydroxy-2-butanone 4-phosphate, the penultimate step in the biosynthesis of riboflavin.

The biosynthesis of one riboflavin molecule requires one molecule of GTP and two molecules of ribulose 5-phosphate as substrates. The final step in the biosynthesis of the vitamin involves the dismutation of 6,7-dimethyl-8-ribityllumazine catalyzed by riboflavin synthase (RS). The second product, 5-amino-6-ribitylamino-2,4(1H,3H)-pyrimidinedione, is recycled in the biosynthetic pathway by 6,7-dimethyl-8-ribityllumazine synthase [PMID: 18298940]. N-[2,4-dioxo-6-d-ribitylamino-1,2,3,4-tetrahydropyrimidin-5-yl]oxalamic acid derivatives inhibit riboflavin synthase [PMID: 18331058].

This superfamily includes both lumazine synthase and riboflavin synthase. Both share sequence similarity, they appear to have diverged early in the evolution of archaea from a common ancestor.

The lumazine synthase structure is a pentamer consisting of five subunits related by 5-fold local symmetry [PMID: 15723519]. Each subunits consists of a three layers (alpha/beta/alpha) with a parallel beta-sheet of four strands.

GO terms

Biological Process

GO:0009231 riboflavin biosynthetic process

Molecular Function

No terms assigned in this category.

Cellular Component

GO:0009349 riboflavin synthase complex

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.