PDBsum entry: 1haw

Reductase

PDB id: 1haw

Contents

Protein chain

336 a.a. *

Metals

CU1

Waters ×149

* Residue conservation analysis

PDB id:

1haw

Name:

Reductase

Title:

X-ray structure of a blue copper nitrite reductase at high ph and in copper free form at 1.9a resolution

Structure:

Dissimilatory copper-containing nitrite reductase. Chain: a. Synonym: nir. Other_details: copper

Source:

Alcaligenes xylosoxydans. Organism_taxid: 85698. Strain: xylosoxidans. Cellular_location: periplasm

Biol. unit:

Trimer (from PDB file)

Resolution:

1.9Å R-factor: 0.172 R-free: 0.199

Authors:

M.J.Ellis,F.E.Dodd,R.W.Strange,M.Prudencio,R.R.Sawerseady, S.S.Hasnain

Key ref:

M.J.Ellis et al. (2001). X-ray structure of a blue copper nitrite reductase at high pH and in copper-free form at 1.9 A resolution. Acta Crystallogr D Biol Crystallogr, 57, 1110-1118. PubMed id: 11468394 DOI: 10.1107/S0907444901008654

Date:

09-Apr-01 Release date: 02-Aug-01

Protein chain

O68601  (O68601_ALCXX) -  Dissimilatory copper-containing nitrite reductase

Seq: 360 a.a.

Struc: 336 a.a.

 Gene Ontology (GO) functional annotation 

• Biological process: nitrogen compound metabolic process (2 terms)
• Biochemical function: oxidoreductase activity (3 terms)

DOI no: 10.1107/S0907444901008654

Acta Crystallogr D Biol Crystallogr 57:1110-1118 (2001)

PubMed id: 11468394

X-ray structure of a blue copper nitrite reductase at high pH and in copper-free form at 1.9 A resolution.

M.J.Ellis, F.E.Dodd, R.W.Strange, M.Prudêncio, G.Sawers, R.R.Eady, S.S.Hasnain.

ABSTRACT

Copper-containing nitrite reductases possess a trimeric structure where the catalytic Cu site, located at the monomer-monomer interface, resembles the catalytic sites of a number of Zn enzymes. Nitrite reductase from Alcaligenes xylosoxidans has optimum activity at pH 5.2 which decreases to a negligible level at pH 8. The structure of this nitrite reductase has previously been determined at pH 4.6. It has now been crystallized under new conditions at pH 8.5. Its crystallographic structure provides a structural explanation for the greatly reduced activity of the enzyme at high pH. Characterization of overexpressed protein in solution by EXAFS suggested that the protein lacked Cu in the catalytic type 2 Cu site and that the site was most probably occupied by Zn. Using the anomalous signals from Cu and Zn, the crystal structure revealed that the expressed protein was devoid of Cu in the catalytic site and that only a trace amount (<10%) of Zn was present at this site in the crystal. Despite the close structural similarity of the catalytic site to a number of Zn enzymes, these data suggest that Zn, if it binds at the catalytic copper site, binds weakly in nitrite reductase.

Selected figure(s)

Figure 2.
Figure 2 The type 1 Cu site (blue) and the surface hydrophobic residues (green) of (a) ntNiR and (b) rcNiR. The surface above the type 1 Cu site in ntNiR is in a closed conformation. The disordered Met135 (dual conformations shown in red and green) and Met87 cover the type 1 Cu site. In rcNiR, Met135 and Met87 both adopt single conformations which lead to an opening of the surface and the binding of a water (W6) to His139 N 2. A water found in this position in the cupredoxin azurin is associated with electron transfer into the type 1 Cu site (Baker, 1988[Baker, E. N. (1988). J. Mol. Biol. 203, 1071-1075.]; Dodd et al., 1995[Dodd, F. E., Hasnain, S. S., Abraham, Z. H. L., Eady, R. R. & Smith, B. E. (1995). Acta Cryst. D51, 1052-1064.]).

Figure 5.
Figure 5 A comparison is made of the Cu K absorption edge of rcNiR with a reference spectra of the oxidized and reduced type 1 Cu site of ntNiR. The absence of the enhanced `white-line' feature at the rcNiR absorption edge shows that the Cu is reduced.

The above figures are reprinted by permission from the IUCr: Acta Crystallogr D Biol Crystallogr (2001, 57, 1110-1118) copyright 2001.

Figures were selected by an automated process.