4KNT: Copper Nitrite Reductase From Nitrosomonas Europaea Ph 8.5

Nitrifier denitrification is the conversion of nitrite to nitrous oxide by ammonia-oxidizing organisms. This process, which is distinct from denitrification, is active under aerobic conditions in the model nitrifier Nitrosomonas europaea. The central enzyme of the nitrifier dentrification pathway is a copper nitrite reductase (CuNIR). To understand how a CuNIR, typically inactivated by oxygen, functions in this pathway, the enzyme isolated directly from N. europaea (NeNIR) was biochemically and structurally characterized. NeNIR reduces nitrite at a similar rate to other CuNIRs but appears to be oxygen tolerant. Crystal structures of oxidized and reduced NeNIR reveal a substrate channel to the active site that is much more restricted than channels in typical CuNIRs. In addition, there is a second fully hydrated channel leading to the active site that likely acts a water exit pathway. The structure is minimally affected by changes in pH. Taken together, these findings provide insight into the molecular basis for NeNIR oxygen tolerance.
PDB ID: 4KNTDownload
MMDB ID: 112083
PDB Deposition Date: 2013/5/10
Updated in MMDB: 2013/09
Experimental Method:
x-ray diffraction
Resolution: 1.9  Å
Source Organism:
Similar Structures:
Biological Unit for 4KNT: trimeric; determined by author and by software (PISA)
Molecular Components in 4KNT
Label Count Molecule
Proteins (3 molecules)
Multicopper Oxidase Type 1
Molecule annotation
Chemicals (18 molecules)
* Click molecule labels to explore molecular sequence information.

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