Cyanide binding to fully reduced Pseudomonas aeruginosa cd(1) nitrite reductase (Pa cd(1) NiR) has been investigated for the wild-type enzyme and a site-directed mutant in which the active-site His369 was replaced by Ala. This mutation reduces the affinity toward cyanide (by approximately 13-fold) and especially decreases the rate of binding of cyanide to the reduced d(1) heme (by approximately 100-fold). The crystal structure of wild-type reduced Pa cd(1) NiR saturated with cyanide was determined to a resolution of 2.7 A. Cyanide binds to the iron of the d(1) heme, with an Fe-C-N angle of 168 degrees for both subunits of the dimer and only His369 is within hydrogen bonding distance of the nitrogen atom of the ligand. These results suggest that in Pa cd(1) NiR the invariant distal residue His369 plays a dominant role in controlling the binding of anionic ligands and allow the discussion of the mechanism of cyanide binding to the wild-type enzyme.
Cyanide binding to cd(1) nitrite reductase from Pseudomonas aeruginosa: Role of the active-site His369 in ligand stabilization / Sun, W; Arese, Marzia; Brunori, Maurizio; Nurizzo, D; Brown, K; Cambillau, C; Tegoni, M; Cutruzzola', Francesca. - In: BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS. - ISSN 0006-291X. - 291:1(2002), pp. 1-7. [10.1006/bbrc.2002.6391]
Cyanide binding to cd(1) nitrite reductase from Pseudomonas aeruginosa: Role of the active-site His369 in ligand stabilization
ARESE, Marzia;BRUNORI, Maurizio;CUTRUZZOLA', Francesca
2002
Abstract
Cyanide binding to fully reduced Pseudomonas aeruginosa cd(1) nitrite reductase (Pa cd(1) NiR) has been investigated for the wild-type enzyme and a site-directed mutant in which the active-site His369 was replaced by Ala. This mutation reduces the affinity toward cyanide (by approximately 13-fold) and especially decreases the rate of binding of cyanide to the reduced d(1) heme (by approximately 100-fold). The crystal structure of wild-type reduced Pa cd(1) NiR saturated with cyanide was determined to a resolution of 2.7 A. Cyanide binds to the iron of the d(1) heme, with an Fe-C-N angle of 168 degrees for both subunits of the dimer and only His369 is within hydrogen bonding distance of the nitrogen atom of the ligand. These results suggest that in Pa cd(1) NiR the invariant distal residue His369 plays a dominant role in controlling the binding of anionic ligands and allow the discussion of the mechanism of cyanide binding to the wild-type enzyme.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.