Crystal Structure of NAD(P)H:flavin Oxidoreductase From Escherichia Coli

Biochemistry. 1999 Jun 1;38(22):7040-9. doi: 10.1021/bi982849m.


Flavin reductases use flavins as substrates and are distinct from flavoenzymes which have tightly bound flavins. The reduced flavin can serve to reduce ferric complexes and iron proteins. In Escherichia coli, reactivation of ribonucleotide reductase is achieved by reduced flavins produced by flavin reductase. The crystal structure of E. coli flavin reductase reveals that the enzyme structure is similar to the structures of the ferredoxin reductase family of flavoproteins despite very low sequence similarities. The main difference between flavin reductase and structurally related flavoproteins is that there is no binding site for the AMP moiety of FAD. The direction of the helix in the flavin binding domain, corresponding to the phosphate binding helix in the flavoproteins, is also slightly different and less suitable for phosphate binding. Interactions for flavin substrates are instead provided by a hydrophobic isoalloxazine binding site that also contains a serine and a threonine, which form hydrogen bonds to the isoalloxazine of bound riboflavin in a substrate complex.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Monophosphate / chemistry
  • Adenosine Monophosphate / metabolism
  • Amino Acid Sequence
  • Binding Sites
  • Crystallization
  • Crystallography, X-Ray
  • Escherichia coli / enzymology*
  • Evolution, Molecular
  • FMN Reductase
  • Ferredoxin-NADP Reductase / chemistry
  • Ferredoxin-NADP Reductase / metabolism
  • Flavin Mononucleotide / chemistry
  • Flavin Mononucleotide / metabolism
  • Flavin-Adenine Dinucleotide / chemistry
  • Flavin-Adenine Dinucleotide / metabolism
  • Hydrogen Bonding
  • Models, Molecular
  • Molecular Sequence Data
  • NADH, NADPH Oxidoreductases / chemistry*
  • NADH, NADPH Oxidoreductases / metabolism
  • NADP / chemistry
  • NADP / metabolism
  • Phosphates / chemistry
  • Phosphates / metabolism
  • Riboflavin / chemistry
  • Riboflavin / metabolism
  • Sequence Alignment
  • Sequence Homology, Amino Acid


  • Phosphates
  • Flavin-Adenine Dinucleotide
  • Adenosine Monophosphate
  • NADP
  • Flavin Mononucleotide
  • Ferredoxin-NADP Reductase
  • FMN Reductase
  • NADH, NADPH Oxidoreductases
  • Riboflavin

Associated data

  • PDB/1QFJ