Lumazine-binding protein (IPR001783)

Short name: Lumazine-bd

Overlapping homologous superfamilies


Family relationships



The following proteins have been shown [PMID: 1996310, PMID: 1560772] to be structurally and evolutionary related:

  • Riboflavin synthase alpha chain (EC: (RS-alpha) (gene ribC in Escherichia coli, ribB in Bacillus subtilis and Photobacterium leiognathi, RIB5 in yeast. This enzyme synthesises riboflavin from two moles of 6,7- dimethyl-8-(1'-D-ribityl)lumazine (Lum), a pteridine-derivative.
  • Photobacterium phosphoreum lumazine protein (LumP) (gene luxL). LumP is a protein that modulates the colour of the bioluminescence emission of bacterial luciferase. In the presence of LumP, light emission is shifted to higher energy values (shorter wavelength). LumP binds non-covalently to 6,7-dimethyl-8-(1'-D-ribityl)lumazine.
  • Vibrio fischeri yellow fluorescent protein (YFP) (gene luxY). Like LumP, YFP modulates light emission but towards a longer wavelength. YFP binds non-covalently to FMN.
  • Aliivibrio fischeri blue fluorescence protein.

These proteins seem to have evolved from the duplication of a domain of about 100 residues. In its C-terminal section, this domain contains a conserved motif [KR]-V-N-[LI]-E which has been proposed to be the binding site for lumazine (Lum) and some of its derivatives. RS-alpha which binds two molecules of Lum has two perfect copies of this motif, while LumP which binds one molecule of Lum, has a Glu instead of Lys/Arg in the first position of the second copy of the motif. Similarly, YFP, which binds to one molecule of FMN, also seems to have a potentially dysfunctional binding site by substitution of Gly for Glu in the last position of the first copy of the motif.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
  • cd00402 (Riboflavin_synthase_like)