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NorR DNA-binding transcriptional dual regulator

Synonyms: NorR
NorR, NO reduction and detoxification Regulator, is one of several regulatory proteins, such as Fur, SoxR, and OxyR, that are involved in the response to reactive nitrogen species. Under anaerobic and microaerobic conditions it activates transcription of the norVW operon, encoding a nitric oxide (NO)-reducing flavorubredoxin that detoxifies NO |CITS: [16100392][14718666][12529359][11751865][12142437]|.
A norR mutant is completely defective with respect to anaerobic NO detoxification |CITS: [11751865]| and is sensitive to reactive nitrogen intermediates generated from nitroprusside. The norR gene is transcribed divergently from norVW and autoregulated |CITS: [16417519]|. It is activated in the absence of oxygen and by nitrite under anaerobic conditions |CITS: [12586421]|.
NorR is a σ54-dependent transcriptional activator |CITS: [12618438]|. It contains three domains: an N-terminal GAF (cGMP phosphodiesterase, adenylate cyclase, FhlA) domain that is involved in signal sensing |CITS: [16193057][12529359][11032796]|; a central catalytic AAA+ domain that is required for interacting with σ54 and for coupling ATP hydrolysis to promoter DNA melting by RNA polymerase; and a C-terminal domain that contains a helix-turn-helix DNA-binding motif |CITS: [18003617]|.
In the absence of NO, the activity of the central catalytic AAA+ domain of NorR is repressed by direct interaction between the GAF domain and the σ54-interacting region of the AAA+ domain.
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Transcription factor      
TF conformation(s):
Name Conformation Type TF-Effector Interaction Type Apo/Holo Conformation Evidence (Confirmed, Strong, Weak) References
NorR     nd nd
Evolutionary Family: EBP
Connectivity class: Local Regulator
Gene name: norR
  Genome position: 2830775-2832289
  Length: 1515 bp / 504 aa
Operon name: norR
TU(s) encoding the TF:
Transcription unit        Promoter

Regulated gene(s) norR, norV, norW
Multifun term(s) of regulated gene(s) MultiFun Term (List of genes associated to the multifun term)
detoxification (2)
electron carriers (2)
Transcription related (1)
activator (1)
Regulated operon(s) norR, norVW
First gene in the operon(s) norR, norV
Simple and complex regulons FNR,IHF,NarL,NarP,NorR
Simple and complex regulatory phrases Regulatory phrase (List of promoters regulated by the phrase)

Transcription factor binding sites (TFBSs) arrangements       

  Functional conformation Function Promoter Sigma factor Central Rel-Pos Distance to first Gene Genes Sequence LeftPos RightPos Evidence (Confirmed, Strong, Weak) References
  NorR repressor norRp nd -45.0 -63.0 norR
2832346 2832358 [AIBSCS], [BPP], [GEA] [1], [2], [3], [4]
  NorR repressor norRp nd -21.0 -39.0 norR
2832322 2832334 [AIBSCS], [BPP], [GEA] [1], [2], [3], [4]
  NorR repressor norRp nd 1.0 -18.0 norR
2832301 2832313 [AIBSCS], [BPP], [GEA] [1], [2], [3], [4]
  NorR activator norVp Sigma54 -132.0 -169.0 norV, norW
2832301 2832313 [AIBSCS], [BPP], [GEA] [1], [2], [3], [4], [5], [6], [7]
  NorR activator norVp Sigma54 -111.0 -148.0 norV, norW
2832322 2832334 [AIBSCS], [BPP], [GEA] [1], [2], [3], [4], [5], [6], [7]
  NorR activator norVp Sigma54 -87.0 -124.0 norV, norW
2832346 2832358 [AIBSCS], [BPP], [GEA] [1], [2], [3], [4], [5], [6], [7]

Evolutionary conservation of regulatory elements    
     Note: Evolutionary conservation of regulatory interactions and promoters is limited to gammaproteobacteria.
Promoter-target gene evolutionary conservation


 [AIBSCS] Automated inference based on similarity to consensus sequences

 [BPP] Binding of purified proteins

 [GEA] Gene expression analysis


 [1] Justino MC., Goncalves VM., Saraiva LM., 2005, Binding of NorR to three DNA sites is essential for promoter activation of the flavorubredoxin gene, the nitric oxide reductase of Escherichia coli., Biochem Biophys Res Commun. 328(2):540-4

 [2] Tucker N., D'autreaux B., Spiro S., Dixon R., 2005, DNA binding properties of the Escherichia coli nitric oxide sensor NorR: towards an understanding of the regulation of flavorubredoxin expression., Biochem Soc Trans. 33(Pt 1):181-3

 [3] Tucker NP., D'Autr?aux B., Studholme DJ., Spiro S., Dixon R., 2004, DNA binding activity of the Escherichia coli nitric oxide sensor NorR suggests a conserved target sequence in diverse proteobacteria., J Bacteriol. 186(19):6656-60

 [4] Tucker NP., D'autreaux B., Spiro S., Dixon R., 2006, Mechanism of transcriptional regulation by the Escherichia coli nitric oxide sensor NorR., Biochem Soc Trans. 34(Pt 1):191-4

 [5] Gardner AM., Gessner CR., Gardner PR., 2003, Regulation of the nitric oxide reduction operon (norRVW) in Escherichia coli. Role of NorR and sigma54 in the nitric oxide stress response., J Biol Chem. 278(12):10081-6

 [6] Gardner AM., Helmick RA., Gardner PR., 2002, Flavorubredoxin, an inducible catalyst for nitric oxide reduction and detoxification in Escherichia coli., J Biol Chem. 277(10):8172-7

 [7] Hutchings MI., Mandhana N., Spiro S., 2002, The NorR protein of Escherichia coli activates expression of the flavorubredoxin gene norV in response to reactive nitrogen species., J Bacteriol. 184(16):4640-3