4KNT : Copper nitrite reductase from Nitrosomonas europaea pH 8.5

  • T. J. Lawton (Contributor)
  • L. A. Sayavedra-Soto (Contributor)
  • D. J. Arp (Contributor)
  • Amy C Rosenzweig (Contributor)



Experimental Technique/Method:X-RAY DIFFRACTION
Release Date:2013-07-24
Deposition Date:2013-05-10
Revision Date:2013-08-14#2013-09-18
Molecular Weight:96049.95
Macromolecule Type:Protein
Residue Count:855
Atom Site Count:6855

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 available2013

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