Biochemical properties of Paracoccus denitrificans FnrP: Reactions with molecular oxygen and nitric oxide

Crack, Jason, Hutchings, Matthew, Thomson, Andrew and Le Brun, Nicolas ORCID: (2016) Biochemical properties of Paracoccus denitrificans FnrP: Reactions with molecular oxygen and nitric oxide. JBIC Journal of Biological Inorganic Chemistry, 21 (1). pp. 71-82. ISSN 0949-8257

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In Paracoccus denitrificans, three CRP/FNR family regulatory proteins, NarR, NnrR and FnrP, control the switch between aerobic and anaerobic (denitrification) respiration. FnrP is a [4Fe-4S] cluster containing homologue of the archetypal O2 sensor FNR from E. coli and accordingly regulates genes encoding aerobic and anaerobic respiratory enzymes in response to O2, and also NO, availability. Here we show that FnrP undergoes O2-driven [4Fe-4S] to [2Fe-2S] cluster conversion that involves up to 2 O2 per cluster, with significant oxidation of released cluster sulfide to sulfane observed at higher O2 concentrations. The rate of the cluster reaction was found to be ~6-fold lower than that of E. coli FNR, suggesting that FnrP can remain transcriptionally active under microaerobic conditions. This is consistent with a role for FnrP in activating expression of the high O2 affinity cytochrome c oxidase under microaerobic conditions. Cluster conversion resulted in dissociation of the transcriptionally active FnrP dimer into monomers. Therefore, along with E. coli FNR, FnrP belongs to the subset of FNR proteins in which cluster type is correlated with association state. Interestingly, two key charged residues, Arg140 and Asp154, that have been shown to play key roles in the monomer-dimer equilibrium in E. coli FNR are not conserved in FnrP, indicating that different protomer interactions are important for this equilibrium. Finally, the FnrP [4Fe-4S] cluster is shown to undergo reaction with multiple NO molecules, resulting in iron nitrosyl species and dissociation into monomers.

Item Type: Article
Additional Information: © The Author(s) 2016. This article is published with open access at
Uncontrolled Keywords: fumarate–nitrate reduction regulator,gene regulation,iron–sulfur cluster ,oxygen ,nitric oxide
Faculty \ School: Faculty of Science > School of Chemistry
Faculty of Science > School of Biological Sciences
UEA Research Groups: Faculty of Science > Research Groups > Biophysical Chemistry (former - to 2017)
Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences
Faculty of Science > Research Groups > Molecular Microbiology
Faculty of Science > Research Centres > Centre for Molecular and Structural Biochemistry
Faculty of Science > Research Groups > Organisms and the Environment
Faculty of Science > Research Groups > Chemistry of Life Processes
Depositing User: Pure Connector
Date Deposited: 02 Feb 2016 13:09
Last Modified: 11 May 2023 23:59
DOI: 10.1007/s00775-015-1326-7


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