A novel type of catalytic copper cluster in nitrous oxide reductase

Nat Struct Biol. 2000 Mar;7(3):191-5. doi: 10.1038/73288.


Nitrous oxide (N20) is a greenhouse gas, the third most significant contributor to global warming. As a key process for N20 elimination from the biosphere, N20 reductases catalyze the two-electron reduction of N20 to N2. These 2 x 65 kDa copper enzymes are thought to contain a CuA electron entry site, similar to that of cytochrome c oxidase, and a CuZ catalytic center. The copper anomalous signal was used to solve the crystal structure of N20 reductase from Pseudomonas nautica by multiwavelength anomalous dispersion, to a resolution of 2.4 A. The structure reveals that the CuZ center belongs to a new type of metal cluster, in which four copper ions are liganded by seven histidine residues. N20 binds to this center via a single copper ion. The remaining copper ions might act as an electron reservoir, assuring a fast electron transfer and avoiding the formation of dead-end products.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Azurin / analogs & derivatives
  • Azurin / metabolism
  • Binding Sites
  • Catalytic Domain
  • Copper / chemistry*
  • Copper / metabolism*
  • Crystallography, X-Ray
  • Dimerization
  • Histidine / metabolism
  • Hydrogen Bonding
  • Models, Molecular
  • Molecular Sequence Data
  • Nitrous Oxide / metabolism
  • Oxidation-Reduction
  • Oxidoreductases / chemistry*
  • Oxidoreductases / metabolism*
  • Protein Conformation
  • Protein Folding
  • Pseudomonas / enzymology*
  • Structure-Activity Relationship


  • cupredoxin
  • Azurin
  • Histidine
  • Copper
  • Oxidoreductases
  • nitrous oxide reductase
  • Nitrous Oxide

Associated data

  • PDB/1QNI