Riboflavin kinase

riboflavin kinase
ExPASy		NiceZyme view
KEGG	KEGG entry
MetaCyc	metabolic pathway
PRIAM	profile
PDB structures	RCSB PDB PDBe PDBsum
Gene Ontology	AmiGO / QuickGO
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Riboflavin Kinase
SCOP2		1mrz / SCOPe / SUPFAM
Available protein structures: Pfam   structures / ECOD   PDB RCSB PDB; PDBe; PDBj PDBsum structure summary

Riboflavin kinase
Identifiers
Symbol	Riboflavin_kinase
Pfam	PF01687
InterPro	IPR015865
Available protein structures: Pfam   structures / ECOD   PDB RCSB PDB; PDBe; PDBj PDBsum structure summary PDB PDB: 1mrz​ PDB: 1n05​ PDB: 1n06​ PDB: 1n07​ PDB: 1n08​ PDB: 1nb0​ PDB: 1nb9​ PDB: 1p4m​ PDB: 1q9s​ PDB: 1s4m​

In

ATP + riboflavin ${\displaystyle \rightleftharpoons }$ ADP + FMN

Thus, the two

.

Riboflavin is converted into catalytically active cofactors (FAD and FMN) by the actions of riboflavin kinase (EC 2.7.1.26), which converts it into FMN, and FAD synthetase (EC 2.7.7.2), which adenylates FMN to FAD. Eukaryotes usually have two separate enzymes, while most prokaryotes have a single bifunctional protein that can carry out both catalyses, although exceptions occur in both cases. While eukaryotic monofunctional riboflavin kinase is orthologous to the bifunctional prokaryotic enzyme,^[2] the monofunctional FAD synthetase differs from its prokaryotic counterpart, and is instead related to the PAPS-reductase family.^[3] The bacterial FAD synthetase that is part of the bifunctional enzyme has remote similarity to nucleotidyl transferases and, hence, it may be involved in the adenylylation reaction of FAD synthetases.^[4]

This enzyme belongs to the family of

.

However, archaeal riboflavin kinases (EC 2.7.1.161) in general utilize CTP rather than ATP as the donor nucleotide, catalyzing the reaction

CTP + riboflavin ${\displaystyle \rightleftharpoons }$ CDP + FMN ^[5]

Riboflavin kinase can also be isolated from other types of bacteria, all with similar function but a different number of amino acids.

Structure

The complete enzyme arrangement can be observed with

. The riboflavin kinase enzyme isolated from Thermoplasma acidophilum contains 220 amino acids. The structure of this enzyme has been determined X-ray crystallography at a resolution of 2.20 Å. Its secondary structure contains 69 residues (30%) in alpha helix form, and 60 residues (26%) a beta sheet conformation. The enzyme contains a magnesium binding site at amino acids 131 and 133, and a Flavin mononucleotide binding site at amino acids 188 and 195.

As of late 2007, 14

.

References

Further reading

• CHASSY BM, ARSENIS C, MCCORMICK DB (1965). "The Effect of the Length of the Side Chain of Flavins on Reactivity with Flavokinase". J. Biol. Chem. 240 (3): 1338–40.
  PMID 14284745
  .
• GIRI KV, KRISHNASWAMY PR, RAO NA (1958). "Studies on plant flavokinase". Biochem. J. 70 (1): 66–71.
  PMID 13584303
  .
• KEARNEY EB (1952). "The interaction of yeast flavokinase with riboflavin analogues". J. Biol. Chem. 194 (2): 747–54.
  PMID 14927668
  .
• McCormick DB; Butler RC (1962). "Substrate specificity of liver flavokinase". Biochim. Biophys. Acta. 65 (2): 326–332.
  doi:10.1016/0006-3002(62)91051-X
  .
• Sandoval FJ, Roje S (2005). "An FMN hydrolase is fused to a riboflavin kinase homolog in plants". J. Biol. Chem. 280 (46): 38337–45.
  PMID 16183635
  .
• Solovieva IM, Tarasov KV, Perumov DA (February 2003). "Main physicochemical features of monofunctional flavokinase from Bacillus subtilis". Biochemistry (Moscow). 68 (2): 177–81.
  S2CID 35221624
  .
• Solovieva, I.M.; Kreneva, R.A.; Leak, D.J.; Perumov, D. A. (January 1999). "The ribR gene encodes a monofunctional riboflavin kinase which is involved in regulation of the Bacillus subtilis riboflavin operon". Microbiology. 145: 67–73.
  PMID 10206712
  .

This article incorporates text from the public domain Pfam and InterPro: IPR015865