Haem-ligand switching during catalysis in crystals of a nitrogen-cycle enzyme

Pamela A. Williams (), Vilmos Fülöp (), Elspeth F. Garman, Neil F. W. Saunders, Stuart J. Ferguson and Janos Hajdu ()
Additional contact information
Pamela A. Williams: Laboratory of Molecular Biophysics, University of Oxford
Vilmos Fülöp: Laboratory of Molecular Biophysics, University of Oxford
Elspeth F. Garman: Laboratory of Molecular Biophysics, University of Oxford
Neil F. W. Saunders: University of Oxford
Stuart J. Ferguson: Oxford Centre for Molecular Sciences, University of Oxford
Janos Hajdu: Laboratory of Molecular Biophysics, University of Oxford

Nature, 1997, vol. 389, issue 6649, 406-412

Abstract: Abstract Cytochrome cd1 nitrite reductase catalyses the conversion of nitrite to nitric oxide in the nitrogen cycle1,2. The crystal structure of the oxidized enzyme3,4 shows that the d1 haem iron of the active site is ligated by His/Tyr side chains, and the c haem iron is ligated by a His/His ligand pair. Here we show that both haems undergo re-ligation during catalysis. Upon reduction, the tyrosine ligand of the d1 haem is released to allow substrate binding. Concomitantly, a refolding of the cytochrome c domain takes place, resulting in an unexpected change of the c haem iron coordination from His 17/His 69 to Met106/His69. This step is similar to the last steps in the folding of cytochrome c5,6,7,8. The changes must affect the redox potential of the haems, and suggest a mechanism by which internal electron transfer is regulated. Structures of reaction intermediates show how nitric oxide is formed and expelled from the active-site iron, as well as how both haems return to their starting coordination. These results show how redox energy can be switched into conformational energy within a haem protein.

Date: 1997
References: Add references at CitEc
Citations:

Downloads: (external link)
https://www.nature.com/articles/38775 Abstract (text/html)
Access to the full text of the articles in this series is restricted.

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:nat:nature:v:389:y:1997:i:6649:d:10.1038_38775

Ordering information: This journal article can be ordered from
https://www.nature.com/

DOI: 10.1038/38775

Access Statistics for this article

Nature is currently edited by Magdalena Skipper

More articles in Nature from Nature
Bibliographic data for series maintained by Sonal Shukla () and Springer Nature Abstracting and Indexing ().