1FS9: Cytochrome C Nitrite Reductase From Wolinella Succinogenes-Azide Complex

Cytochrome c nitrite reductase catalyzes the 6-electron reduction of nitrite to ammonia. This second part of the respiratory pathway of nitrate ammonification is a key step in the biological nitrogen cycle. The x-ray structure of the enzyme from the epsilon-proteobacterium Wolinella succinogenes has been solved to a resolution of 1.6 A. It is a pentaheme c-type cytochrome whose heme groups are packed in characteristic motifs that also occur in other multiheme cytochromes. Structures of W. succinogenes nitrite reductase have been obtained with water bound to the active site heme iron as well as complexes with two inhibitors, sulfate and azide, whose binding modes and inhibitory functions differ significantly. Cytochrome c nitrite reductase is part of a highly optimized respiratory system found in a wide range of Gram-negative bacteria. It reduces both anionic and neutral substrates at the distal side of a lysine-coordinated high-spin heme group, which is accessible through two different channels, allowing for a guided flow of reaction educt and product. Based on sequence comparison and secondary structure prediction, we have demonstrated that cytochrome c nitrite reductases constitute a protein family of high structural similarity.
PDB ID: 1FS9Download
MMDB ID: 15418
PDB Deposition Date: 2000/9/8
Updated in MMDB: 2012/11
Experimental Method:
x-ray diffraction
Resolution: 2  Å
Source Organism:
Similar Structures:
Biological Unit for 1FS9: dimeric; determined by author and by software (PISA,PQS)
Molecular Components in 1FS9
Label Count Molecule
Proteins (2 molecules)
Cytochrome C Nitrite Reductase
Molecule annotation
Chemicals (19 molecules)
* Click molecule labels to explore molecular sequence information.

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