Mechanism of transcriptional regulation by the Escherichia coli nitric oxide sensor NorR

Nitric oxide (NO) is a highly reactive water-soluble gas encountered by bacteria endogenously as an intermediate of denitrification and exogenously as one of the radical species deployed by macrophages against invading pathogens. Bacteria therefore require a mechanism to detoxify NO. Escherichia coli flavorubredoxin and its associated oxidoreductase, encoded by the norV and norW genes respectively, reduces NO to nitrous oxide under anaerobic conditions. Transcription of the norVW genes is activated in response to NO by the σ54-dependent regulator NorR, a member of the prokaryotic enhancer binding protein family. NorR binds co-operatively to three enhancer sites to regulate transcription of both norVW and the divergently transcribed norR gene. In the present paper, we show that disruption of any one of the three GT-(N7)-AC NorR binding sites in the norR–norVW intergenic region prevents both activation of norVW expression and autogenous repression of the norR promoter by NorR. We have recently demonstrated that the N-terminal GAF (cGMP-specific and -stimulated phosphodiesterases, Anabaena adenylate cyclases and Escherichia coli FhlA) domain of NorR contains a non-haem mononuclear iron centre and senses NO by formation of a mono-nitrosyl iron complex. Site-directed mutagenesis has identified candidate protein ligands to the ferrous iron centre in the GAF domain.

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Water-Soluble Dinitrosyl Iron Complex (DNIC): a Nitric Oxide Vehicle Triggering Cancer Cell Death via Apoptosis

Inorganic Chemistry ◽

10.1021/acs.inorgchem.6b01562 ◽

2016 ◽

Vol 55 (18) ◽

pp. 9383-9392 ◽

Cited By ~ 25

Author(s):

Shou-Cheng Wu ◽

Chung-Yen Lu ◽

Yi-Lin Chen ◽

Feng-Chun Lo ◽

Ting-Yin Wang ◽

...

Keyword(s):

Nitric Oxide ◽

Cell Death ◽

Cancer Cell ◽

Iron Complex ◽

Water Soluble ◽

Dinitrosyl Iron Complex ◽

Cancer Cell Death ◽

Dinitrosyl Iron

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Synthesis, properties, and antibacterial activity of a new nitric oxide donor — a nitrosyl iron complex with 5-phenyl-1H-1,2,4-triazole-3-thiol

Russian Chemical Bulletin ◽

10.1007/s11172-019-2691-0 ◽

2019 ◽

Vol 68 (12) ◽

pp. 2225-2231

Author(s):

N. A. Sanina ◽

V. A. Mumyatova ◽

A. A. Terent´ev ◽

R. B. Morgunov ◽

N. S. Ovanesyan ◽

...

Keyword(s):

Nitric Oxide ◽

Antibacterial Activity ◽

Iron Complex ◽

Nitric Oxide Donor ◽

Synthesis Properties ◽

Nitrosyl Iron Complex

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Noncovalently functionalized water-soluble multiwall-nanotubes through azocarmine B and their application in nitric oxide sensor

Electrochemistry Communications ◽

10.1016/j.elecom.2007.10.027 ◽

2008 ◽

Vol 10 (1) ◽

pp. 90-94 ◽

Cited By ~ 19

Author(s):

Dongyun Zheng ◽

Chengguo Hu ◽

Yanfen Peng ◽

Wanqing Yue ◽

Shengshui Hu

Keyword(s):

Nitric Oxide ◽

Water Soluble ◽

Nitric Oxide Sensor ◽

Multiwall Nanotubes

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DNA Binding Activity of the Escherichia coli Nitric Oxide Sensor NorR Suggests a Conserved Target Sequence in Diverse Proteobacteria

Journal of Bacteriology ◽

10.1128/jb.186.19.6656-6660.2004 ◽

2004 ◽

Vol 186 (19) ◽

pp. 6656-6660 ◽

Cited By ~ 41

Author(s):

Nicholas P. Tucker ◽

Benoît D'Autréaux ◽

David J. Studholme ◽

Stephen Spiro ◽

Ray Dixon

Keyword(s):

Nitric Oxide ◽

Escherichia Coli ◽

Binding Sites ◽

Consensus Sequence ◽

Transcription Unit ◽

Binding Activity ◽

Integration Host Factor ◽

Target Sequence ◽

Dna Binding Activity ◽

Nitric Oxide Sensor

ABSTRACT The Escherichia coli nitric oxide sensor NorR was shown to bind to the promoter region of the norVW transcription unit, forming at least two distinct complexes detectable by gel retardation. Three binding sites for NorR and two integration host factor binding sites were identified in the norR-norV intergenic region. The derived consensus sequence for NorR binding sites was used to search for novel members of the E. coli NorR regulon and to show that NorR binding sites are partially conserved in other members of the proteobacteria.

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Interaction of nitric oxide with non-haem iron sites of Escherichia coli bacterioferritin: reduction of nitric oxide to nitrous oxide and oxidation of iron(II) to iron(III)

Biochemical Journal ◽

10.1042/bj3260173 ◽

1997 ◽

Vol 326 (1) ◽

pp. 173-179 ◽

Cited By ~ 18

Author(s):

Nick E. LE BRUN ◽

Simon C. ANDREWS ◽

Geoffrey R. MOORE ◽

Andrew J. THOMSON

Keyword(s):

Nitric Oxide ◽

Metal Binding ◽

Iron Complex ◽

Sodium Ascorbate ◽

Reduction Of No ◽

Mononuclear Iron ◽

Iron Nitrosyl ◽

Dinitrosyl Iron ◽

Report Data ◽

Head Space Analysis

The bacterioferritin (BFR) of Escherichia coliconsists of 24 identical subunits, each containing a dinuclear metal-binding site consisting of two histidines and four carboxylic acid residues. Earlier studies showed that the characterization of iron binding to BFR could be aided by EPR analysis of iron–nitrosyl species resulting from the addition of NO to the protein [Le Brun, Cheesman, Andrews, Harrison, Guest, Moore and Thomson (1993) FEBS Lett. 323, 261–266]. We now report data from gas chromatographic head space analysis combined with EPR spectroscopy to show that NO is not an inert probe: iron(II)–BFR catalyses the reduction of NO to N2O, resulting in oxidation of iron(II) at the dinuclear centre and the subsequent detection of mononuclear iron(III). In the presence of excess reductant (sodium ascorbate), iron(II)–BFR also catalyses the reduction of NO to N2O, giving rise to three mononuclear iron–nitrosyl species which are detectable by EPR. One of these, a dinitrosyl–iron complex of S = ½, present at a maximum of one per subunit, is shown by EPR studies of site-directed variants of BFR not to be located at the dinuclear centre. This is consistent with a proposal that the diferric form of the centre is unstable and breaks down to form mononuclear iron species.

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Nitric oxide (NO) reactivity studies on mononuclear iron(ii) complexes supported by a tetradentate Schiff base ligand

RSC Advances ◽

10.1039/c6ra21659e ◽

2016 ◽

Vol 6 (116) ◽

pp. 115326-115333 ◽

Cited By ~ 2

Author(s):

Nidhi Tyagi ◽

Ovender Singh ◽

Udai P. Singh ◽

Kaushik Ghosh

Keyword(s):

Nitric Oxide ◽

Schiff Base ◽

Schiff Base Ligand ◽

Iron Complex ◽

Mononuclear Iron ◽

Tetradentate Schiff Base ◽

Tetradentate Ligands ◽

Vis Spectroscopy

Mononuclear iron(ii) complexes were synthesised and characterized from tetradentate ligands. The reactivity of NO afforded ligand nitrated iron(ii) complex along with the in situ formation of an unstable nitrosylated iron complex which was monitored by UV-vis spectroscopy.

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Mutations Affecting Export and Activity of Cytolysin A from Escherichia coli

Journal of Bacteriology ◽

10.1128/jb.01283-09 ◽

2010 ◽

Vol 192 (15) ◽

pp. 4001-4011 ◽

Cited By ~ 15

Author(s):

Albrecht Ludwig ◽

Guido Völkerink ◽

Christine von Rhein ◽

Susanne Bauer ◽

Elke Maier ◽

...

Keyword(s):

Escherichia Coli ◽

Lipid Bilayer ◽

Hemolytic Activity ◽

Water Soluble ◽

Site Directed Mutagenesis ◽

Tail Domain ◽

Lipid Bilayer Membranes ◽

Hydrophobic Region ◽

Protein Toxin ◽

Head Domain

ABSTRACT Cytolysin A (known as ClyA, HlyE, and SheA) is a cytolytic pore-forming protein toxin found in several Escherichia coli and Salmonella enterica strains. The structure of its water-soluble monomeric form and that of dodecameric ClyA pores is known, but the mechanisms of ClyA export from bacterial cells and of pore assembly are only partially understood. Here we used site-directed mutagenesis to study the importance of different regions of the E. coli ClyA protein for export and activity. The data indicate that ClyA translocation to the periplasm requires several protein segments located closely adjacent to each other in the “tail” domain of the ClyA monomer, namely, the N- and C-terminal regions and the hydrophobic sequence ranging from residues 89 to 101. Deletion of most of the “head” domain of the monomer (residues 181 to 203), on the other hand, did not strongly affect ClyA secretion, suggesting that the tail domain plays a particular role in export. Furthermore, we found that the N-terminal amphipathic helix αA1 of ClyA is crucial for the formation and the properties of the transmembrane channel, and hence for hemolytic activity. Several mutations affecting the C-terminal helix αG, the “β-tongue” region in the head domain, or the hydrophobic region in the tail domain of the ClyA monomer strongly impaired the hemolytic activity and reduced the activity toward planar lipid bilayer membranes but did not totally prevent formation of wild-type-like channels in these artificial membranes. The latter regions thus apparently promote membrane interaction without being directly required for pore formation in a lipid bilayer.

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Transcriptional regulation by the dedicated nitric oxide sensor, NorR: a route towards NO detoxification

Biochemical Society Transactions ◽

10.1042/bst0390289 ◽

2011 ◽

Vol 39 (1) ◽

pp. 289-293 ◽

Cited By ~ 22

Author(s):

Matthew Bush ◽

Tamaswati Ghosh ◽

Nicholas Tucker ◽

Xiaodong Zhang ◽

Ray Dixon

Keyword(s):

Nitric Oxide ◽

Transcriptional Activation ◽

Nitrosative Stress ◽

Regulatory Domain ◽

Atpase Domain ◽

Nitric Oxide Sensor ◽

Enhancer Binding Protein ◽

Σ Factor ◽

Oligomeric Complex ◽

Haem Iron

A flavorubredoxin and its associated oxidoreductase (encoded by norV and norW respectively) detoxify NO (nitric oxide) to form N2O (nitrous oxide) under anaerobic conditions in Escherichia coli. Transcription of the norVW genes is activated in response to NO by the σ54-dependent regulator and dedicated NO sensor, NorR, a member of the bacterial enhancer-binding protein family. In the absence of NO, the catalytic activity of the central ATPase domain of NorR is repressed by the N-terminal regulatory domain that contains a non-haem iron centre. Binding of NO to this centre results in the formation of a mononitrosyl iron species, enabling the activation of ATPase activity. Our studies suggest that the highly conserved GAFTGA loop in the ATPase domain, which engages with the alternative σ factor σ54 to activate transcription, is a target for intramolecular repression by the regulatory domain. Binding of NorR to three conserved enhancer sites upstream of the norVW promoter is essential for transcriptional activation and promotes the formation of a stable higher-order NorR nucleoprotein complex. We propose that enhancer-driven assembly of this oligomeric complex, in which NorR apparently forms a DNA-bound hexamer in the absence of NO, provides a ‘poised’ system for transcriptional activation that can respond rapidly to nitrosative stress.

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