1L9R

CRYSTAL STRUCTURE OF THE I257M VARIANT OF THE COPPER-CONTAINING NITRITE REDUCTASE FROM ALCALIGENES FAECALIS S-6

Summary for 1L9R

• Entry DOI: 10.2210/pdb1l9r/pdb
• Related: 1L9O 1L9P 1L9Q 1L9S 1L9T
• Descriptor: COPPER-CONTAINING NITRITE REDUCTASE, COPPER (II) ION, NITRITE ION, ... (4 entities in total)
• Functional Keywords: cupredoxin fold, oxidoreductase
• Biological source: Alcaligenes faecalis
• Cellular location: Periplasm: P38501
• Total number of polymer chains: 3
• Total formula weight: 111209.34

Authors

Boulanger, M.J.,Murphy, M.E.P. (deposition date: 2002-03-26, release date: 2003-02-04, Last modification date: 2024-02-14)

Primary citation

Boulanger, M.J.,Murphy, M.E.P.
Directing the mode of nitrite binding to a copper-containing nitrite reductase from Alcaligenes faecalis S-6: Characterization of an active site isoleucine
PROTEIN SCI., 12:248-256, 2003

PubMed Abstract: Unlike the heme cd(1)-based nitrite reductase enzymes, the molecular mechanism of copper-containing nitrite reductases remains controversial. A key source of controversy is the productive binding mode of nitrite in the active site. To identify and characterize the molecular determinants associated with nitrite binding, we applied a combinatorial mutagenesis approach to generate a small library of six variants at position 257 in nitrite reductase from Alcaligenes faecalis S-6. The activities of these six variants span nearly two orders of magnitude with one variant, I257V, the only observed natural substitution for Ile257, showing greater activity than the native enzyme. High-resolution (> 1.8 A) nitrite-soaked crystal structures of these variants display different modes of nitrite binding that correlate well with the altered activities. These studies identify for the first time that the highly conserved Ile257 in the native enzyme is a key molecular determinant in directing a catalytically competent mode of nitrite binding in the active site. The O-coordinate bidentate binding mode of nitrite observed in native and mutant forms with high activity supports a catalytic model distinct from the heme cd(1) NiRs. (The atomic coordinates for I257V[NO(2)(-)], I257L[NO(2)(-)], I257A[NO(2)(-)], I257T[NO(2)(-)], I257M[NO(2)(-)] and I257G[NO(2)(-)] AfNiR have been deposited in the Protein Data Bank [PDB identification codes are listed in Table 2].)

PubMed: 12538888
DOI: 10.1110/ps.0224503

Experimental method

X-RAY DIFFRACTION (1.78 Å)