A novel type of catalytic copper cluster in nitrous oxide reductase.
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.
Brown
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K
Architecture et Fonction des Macromolécules Biologiques, UPR 9039, CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille CEDEX 20, France.
Tegoni
M
M
Prudêncio
M
M
Pereira
A S
AS
Besson
S
S
Moura
J J
JJ
Moura
I
I
Cambillau
C
C
D000595:Amino Acid Sequence; D001400:Azurin / Q000031:analogs & derivatives / Q000378:metabolism; D001665:Binding Sites; D020134:Catalytic Domain; D003300:Copper / Q000737:chemistry* / Q000378:metabolism*; D018360:Crystallography, X-Ray; D019281:Dimerization; D006639:Histidine / Q000378:metabolism; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009609:Nitrous Oxide / Q000378:metabolism; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry* / Q000378:metabolism*; D011487:Protein Conformation; D017510:Protein Folding; D011549:Pseudomonas / Q000201:enzymology*; D013329:Structure-Activity Relationship
C050107:cupredoxin; D001400:Azurin; D006639:Histidine; D003300:Copper; D010088:Oxidoreductases; C022763:nitrous oxide reductase; D009609:Nitrous Oxide