The nitrite reductase from Pseudomonas aeruginosa: essential role of two active-site histidines in the catalytic and structural properties.

ABSTRACT: Cd(1) nitrite reductase catalyzes the conversion of nitrite to NO in denitrifying bacteria. Reduction of the substrate occurs at the d(1)-heme site, which faces on the distal side some residues thought to be essential for substrate binding and catalysis. We report the results obtained by mutating to Ala the two invariant active site histidines, His-327 and His-369, of the enzyme from Pseudomonas aeruginosa. Both mutants have lost nitrite reductase activity but maintain the ability to reduce O(2) to water. Nitrite reductase activity is impaired because of the accumulation of a catalytically inactive form, possibly because the productive displacement of NO from the ferric d(1)-heme iron is impaired. Moreover, the two distal His play different roles in catalysis; His-369 is absolutely essenti

SUBMITTER: Cutruzzola F 

PROVIDER: S-EPMC30121 | biostudies-literature | 2001 Feb

REPOSITORIES: biostudies-literature