1ET5

CRYSTAL STRUCTURE OF NITRITE REDUCTASE ASP98ASN MUTANT FROM ALCALIGENES FAECALIS S-6

Summary for 1ET5

• Entry DOI: 10.2210/pdb1et5/pdb
• Related: 1AS7 1ET7 1ET8 2AFN
• Descriptor: NITRITE REDUCTASE, COPPER (II) ION, ZINC ION, ... (4 entities in total)
• Functional Keywords: greek key beta barrel domain, oxidoreductase
• Biological source: Alcaligenes faecalis
• Cellular location: Periplasm: P38501
• Total number of polymer chains: 1
• Total formula weight: 37135.57

Authors

Boulanger, M.J.,Kukimoto, M.,Nishiyama, M.,Horinouchi, S.,Murphy, M.E.P. (deposition date: 2000-04-12, release date: 2000-08-24, Last modification date: 2024-02-07)

Primary citation

Boulanger, M.J.,Kukimoto, M.,Nishiyama, M.,Horinouchi, S.,Murphy, M.E.
Catalytic roles for two water bridged residues (Asp-98 and His-255) in the active site of copper-containing nitrite reductase.
J.Biol.Chem., 275:23957-23964, 2000

PubMed Abstract: Two active site residues, Asp-98 and His-255, of copper-containing nitrite reductase (NIR) from Alcaligenes faecalis have been mutated to probe the catalytic mechanism. Three mutations at these two sites (D98N, H255D, and H255N) result in large reductions in activity relative to native NIR, suggesting that both residues are involved intimately in the reaction mechanism. Crystal structures of these mutants have been determined using data collected to better than 1. 9-A resolution. In the native structure, His-255 Nepsilon2 forms a hydrogen bond through a bridging water molecule to the side chain of Asp-98, which also forms a hydrogen bond to a water or nitrite oxygen ligated to the active site copper. In the D98N mutant, reorientation of the Asn-98 side chain results in the loss of the hydrogen bond to the copper ligand water, consistent with a negatively charged Asp-98 directing the binding and protonation of nitrite in the native enzyme. An additional solvent molecule is situated between residues 255 and the bridging water in the H255N and H255D mutants and likely inhibits nitrite binding. The interaction of His-255 with the bridging water appears to be necessary for catalysis and may donate a proton to reaction intermediates in addition to Asp-98.

PubMed: 10811642
DOI: 10.1074/jbc.M001859200

Experimental method

X-RAY DIFFRACTION (1.9 Å)