Structural insights into the function of a thermostable copper-containing nitrite reductase.
J Biochem
; 155(2): 123-35, 2014 Feb.
Article
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| MEDLINE
| ID: mdl-24293549
ABSTRACT
Copper-containing nitrite reductase (CuNIR) catalyzes the reduction of nitrite (NO(-)2) to nitric oxide (NO) during denitrification. We determined the crystal structures of CuNIR from thermophilic gram-positive bacterium, Geobacillus thermodenitrificans (GtNIR) in chloride- and formate-bound forms of wild type at 1.15 Šresolution and the nitrite-bound form of the C135A mutant at 1.90 Šresolution. The structure of C135A with nitrite displays a unique η(1)-O coordination mode of nitrite at the catalytic copper site (T2Cu), which has never been observed at the T2Cu site in known wild-type CuNIRs, because the mobility of two residues essential to catalytic activity, Asp98 and His244, are sterically restricted in GtNIR by Phe109 on a characteristic loop structure that is found above Asp98 and by an unusually short CH-O hydrogen bond observed between His244 and water, respectively. A detailed comparison of the WT structure with the nitrite-bound C135A structure implies the replacement of hydrogen-bond networks around His244 and predicts the flow path of protons consumed by nitrite reduction. On the basis of these observations, the reaction mechanism of GtNIR through the η(1)-O coordination manner is proposed.
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Base de datos:
MEDLINE
Asunto principal:
Aeromonas
/
Nitrito Reductasas
Tipo de estudio:
Prognostic_studies
Idioma:
En
Revista:
J Biochem
Año:
2014
Tipo del documento:
Article