Nitrite controls the release of nitric oxide in Pseudomonas aeruginosa cd{sub 1} nitrite reductase
- Dipartimento di Scienze Biochimiche 'A. Rossi Fanelli', Sapienza-Universita di Roma, P.le A. Moro, 5 00185 Rome (Italy)
Nitrite reductase (cd{sub 1}NIR) from Pseudomonas aeruginosa, which catalyses the reduction of nitrite to nitric oxide (NO), contains a c-heme as the electron acceptor and a d{sub 1}-heme where catalysis occurs. Reduction involves binding of nitrite to the reduced d{sub 1}-heme, followed by dehydration to yield NO; release of NO and re-reduction of the enzyme close the cycle. Since NO is a powerful inhibitor of ferrous hemeproteins, enzymatic turnover demands the release of NO. We recently discovered that NO dissociation from the ferrous d{sub 1}-heme is fast, showing that cd{sub 1}NIR behaves differently from other hemeproteins. Here we demonstrate for the first time that the physiological substrate nitrite displaces NO from the ferrous enzyme, which enters a new catalytic cycle; this reaction depends on the conserved His369 whose role in substrate stabilization is crucial for catalysis. Thus we suggest that also in vivo the activity of cd{sub 1}NIR is controlled by nitrite.
- OSTI ID:
- 21032982
- Journal Information:
- Biochemical and Biophysical Research Communications, Vol. 363, Issue 3; Other Information: DOI: 10.1016/j.bbrc.2007.09.036; PII: S0006-291X(07)01982-1; Copyright (c) 2007 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0006-291X
- Country of Publication:
- United States
- Language:
- English
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