P0A9E5 · FNR_ECOLI

  • Protein
    Fumarate and nitrate reduction regulatory protein
  • Gene
    fnr
  • Status
    UniProtKB reviewed (Swiss-Prot)
  • Amino acids
  • Protein existence
    Evidence at protein level
  • Annotation score
    5/5

Function

function

Global transcription factor that controls the expression of over 100 target genes in response to anoxia. It facilitates the adaptation to anaerobic growth conditions by regulating the expression of gene products that are involved in anaerobic energy metabolism. When the terminal electron acceptor, O2, is no longer available, it represses the synthesis of enzymes involved in aerobic respiration and increases the synthesis of enzymes required for anaerobic respiration.

Miscellaneous

FNR senses the oxygen concentration directly via the disassembly and reassembly of the [4Fe-4S] clusters. Anaerobic, de novo acquisition of the iron-sulfur cluster converts monomeric, inactive apo-FNR into a dimeric form containing two [4Fe-4S] clusters. This, in turn, enhances the affinity of FNR for specific DNA targets and mediates transcription regulation by establishing direct FNR-RNA polymerase contacts. With the increase in intracellular oxygen concentration, the [4Fe-4S] cluster is oxidized, producing a [2Fe-2S] cluster, which decays to apo-FNR. Apo-FNR [4SH] can be reversibly oxidized to a disulfide form [2SH,S-S], suggesting that FNR may be able to sense oxidative stress as well as normoxia. This interconversion may be mediated by agents such as glutathione or thioredoxin.

Cofactor

[4Fe-4S] cluster (UniProtKB | Rhea| CHEBI:49883 )
Note: Binds 1 [4Fe-4S] cluster per subunit.

Features

Showing features for binding site, dna binding.

TypeIDPosition(s)Description
Binding site20[4Fe-4S] cluster (UniProtKB | ChEBI)
Binding site23[4Fe-4S] cluster (UniProtKB | ChEBI)
Binding site29[4Fe-4S] cluster (UniProtKB | ChEBI)
Binding site122[4Fe-4S] cluster (UniProtKB | ChEBI)
DNA binding197-216H-T-H motif

GO annotations

AspectTerm
Cellular Componentcytosol
Cellular Componentprotein-DNA complex
Molecular Function4 iron, 4 sulfur cluster binding
Molecular FunctionDNA binding
Molecular FunctionDNA-binding transcription activator activity
Molecular FunctionDNA-binding transcription factor activity
Molecular Functioniron-sulfur cluster binding
Molecular Functionmetal ion binding
Molecular Functiontranscription cis-regulatory region binding
Biological Processanaerobic respiration
Biological Processpositive regulation of DNA-templated transcription
Biological Processregulation of DNA-templated transcription
Biological Processresponse to nitric oxide

Keywords

Enzyme and pathway databases

Names & Taxonomy

Protein names

  • Recommended name
    Fumarate and nitrate reduction regulatory protein

Gene names

    • Name
      fnr
    • Synonyms
      nirR
    • Ordered locus names
      b1334, JW1328

Organism names

  • Taxonomic identifier
  • Strains
    • K12 / W3110 / ATCC 27325 / DSM 5911
    • K12 / MG1655 / ATCC 47076
  • Taxonomic lineage
    Bacteria > Pseudomonadota > Gammaproteobacteria > Enterobacterales > Enterobacteriaceae > Escherichia

Accessions

  • Primary accession
    P0A9E5
  • Secondary accessions
    • P03019

Proteomes

Subcellular Location

Keywords

Phenotypes & Variants

Features

Showing features for mutagenesis.

TypeIDPosition(s)Description
Mutagenesis16No effect.
Mutagenesis20Loss of activity.
Mutagenesis22Loss of regulation by O2.
Mutagenesis23Loss of activity.
Mutagenesis28Loss of regulation by O2.
Mutagenesis29Loss of activity.
Mutagenesis43Decrease in activity; no effect on DNA-binding.
Mutagenesis64No effect.
Mutagenesis72Decrease in activity; no effect on DNA-binding.
Mutagenesis73Decrease in activity; no effect on DNA-binding.
Mutagenesis81Decrease in activity; no effect on DNA-binding.
Mutagenesis82Decrease in activity; no effect on DNA-binding.
Mutagenesis85Decrease in activity; no effect on DNA-binding. Trace activity; when associated with P-187.
Mutagenesis86Decrease in activity; no effect on DNA-binding.
Mutagenesis87Decrease in activity; no effect on DNA-binding.
Mutagenesis88Decrease in activity; no effect on DNA-binding.
Mutagenesis93Loss of regulation by O2.
Mutagenesis96Loss of activity.
Mutagenesis118Decrease in activity; no effect on DNA-binding.
Mutagenesis120Decrease in activity; no effect on DNA-binding.
Mutagenesis122Loss of activity.
Mutagenesis140Decrease in activity.
Mutagenesis143Decrease in activity.
Mutagenesis144Decrease in activity due to faulty dimerization.
Mutagenesis145Decrease in activity.
Mutagenesis146Decrease in activity.
Mutagenesis147Decrease in activity due to faulty dimerization.
Mutagenesis150Loss of regulation by O2.
Mutagenesis151Decrease in activity due to faulty dimerization.
Mutagenesis154Loss of regulation by O2.
Mutagenesis158Decrease in activity due to faulty dimerization.
Mutagenesis181Decrease in activity; no effect on DNA-binding.
Mutagenesis186Decrease in activity; no effect on DNA-binding.
Mutagenesis187Decrease in activity; no effect on DNA-binding. Trace activity; when associated with A-85.
Mutagenesis191Decrease in activity; no effect on DNA-binding.

Miscellaneous

PTM/Processing

Features

Showing features for chain.

TypeIDPosition(s)Description
ChainPRO_00001001611-250Fumarate and nitrate reduction regulatory protein

Proteomic databases

Expression

Gene expression databases

Interaction

Subunit

Homodimer.

Protein-protein interaction databases

Structure

Family & Domains

Features

Showing features for region, domain.

TypeIDPosition(s)Description
Region20-29Essential for the oxygen-regulated activity
Region47-50Activating region 2A
Region60-61Activating region 3A
Region71-75Activating region 1A
Region81Activating region 3B
Region85-87Activating region 3C
Region112Activating region 3D
Region116-121Activating region 1B
Region123-124Activating region 2B
Region127-128Activating region 2C
Region140-159Dimerization
Domain164-237HTH crp-type
Region181-191Activating region 1C

Domain

The amino acid residues contacting the FNR target site on the DNA (5'-TTGATNNNNATCAA-3') are located in the putative DNA-recognition helix (alphaF), which contains the FNR motif (EXXSR). Three surface-exposed loops forming activating region 1 (AR1) in the downstream subunit of the dimer contact the C-terminal domain of the alpha subunit (alphaCTD) of RNA polymerase for activation of class I promoters (the 161-121 loop is the major AR1 activating determinant). At class II promoters, the AR1 of the upstream subunit contacts alphaCTD, promoting open complex formation; activating region 3 (AR3) of the downstream subunit contacts region 4 of the sigma70 subunit of RNA polymerase, to effect direct activation. At promoters repressed by FNR, tandem FNR dimers might interact with each other at AR1 to restrict access to a promoter or jam the promoter by their dual interaction with RNA polymerase alphaCTD.

Phylogenomic databases

Family and domain databases

Sequence

  • Sequence status
    Complete
  • Length
    250
  • Mass (Da)
    27,967
  • Last updated
    2005-07-19 v1
  • Checksum
    33F7BFA2972FF703
MIPEKRIIRRIQSGGCAIHCQDCSISQLCIPFTLNEHELDQLDNIIERKKPIQKGQTLFKAGDELKSLYAIRSGTIKSYTITEQGDEQITGFHLAGDLVGFDAIGSGHHPSFAQALETSMVCEIPFETLDDLSGKMPNLRQQMMRLMSGEIKGDQDMILLLSKKNAEERLAAFIYNLSRRFAQRGFSPREFRLTMTRGDIGNYLGLTVETISRLLGRFQKSGMLAVKGKYITIENNDALAQLAGHTRNVA

Mass Spectrometry

Molecular mass is 26,823 Da. Determined by Electrospray.

Keywords

Sequence databases

Nucleotide SequenceProtein SequenceMolecule TypeStatus
J01608
EMBL· GenBank· DDBJ
AAA87981.1
EMBL· GenBank· DDBJ
Genomic DNA Sequence problems.
U00096
EMBL· GenBank· DDBJ
AAC74416.1
EMBL· GenBank· DDBJ
Genomic DNA
AP009048
EMBL· GenBank· DDBJ
BAA14927.1
EMBL· GenBank· DDBJ
Genomic DNA

Genome annotation databases

Similar Proteins

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