Description
Experimental Technique/Method:X-RAY DIFFRACTION
Resolution:2.2
Classification:OXIDOREDUCTASE
Release Date:2013-07-24
Deposition Date:2013-05-10
Revision Date:2013-08-14#2013-09-18
Molecular Weight:190215.62
Macromolecule Type:Protein
Residue Count:1710
Atom Site Count:13372
DOI:10.2210/pdb4kns/pdb
Abstract:
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.
Resolution:2.2
Classification:OXIDOREDUCTASE
Release Date:2013-07-24
Deposition Date:2013-05-10
Revision Date:2013-08-14#2013-09-18
Molecular Weight:190215.62
Macromolecule Type:Protein
Residue Count:1710
Atom Site Count:13372
DOI:10.2210/pdb4kns/pdb
Abstract:
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.
| Date made available | 2013 |
|---|---|
| Publisher | RCSB-PDB |