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RbsR DNA-binding transcriptional dual regulator

Synonyms: RbsR-D-ribose, RbsR
The transcription factor RbsR, for Ribose Repressor, is negatively autoregulated and controls the transcription of the operon involved in ribose catabolism and transport [1, 3, 4] Transcription of this operon is induced when E. coli is grown in the absence of glucose and when the physiological inducer D-ribose binds to the RbsR repressor [4, 5] When D-ribose binds to RbsR, the protein becomes inactive because the binding affinity of RbsR decreases [1]
RbsR represses not only the rbs operon for transport and utilization of D-ribose but also the de novo synthesis of purine nucleotides from D-ribose 5-phosphate. In the presence of the inducer D-ribose, RbsR activates the salvage pathway of purine nucleotide synthesis [2]
Although little is known about the mechanism of regulation of the RbsR transcription factor, Mauzy et al. in 1992 demonstrated that this regulator acts as a repressor by binding to cis-acting elements, which have a conserved inverted repeat sequence and overlap the rbsD promoter [1]
RbsR belongs to the GalR/LacI family, which forms a bundle of four helices characteristic of proteins of an HTH DNA contact motif.
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Transcription factor      
TF conformation(s):
Name Conformation Type TF-Effector Interaction Type Apo/Holo Conformation Evidence (Confirmed, Strong, Weak) References
RbsR Functional   Apo [BPP], [IDA], [IPI] [1]
RbsR-D-ribose Non-Functional Allosteric Holo [BPP], [IDA], [IPI] [1]
Evolutionary Family: GalR/LacI
Sensing class: External sensing using transported metabolites
Connectivity class: Local Regulator
Gene name: rbsR
  Genome position: 3938227-3939219
  Length: 993 bp / 330 aa
Operon name: rbsDACBKR
TU(s) encoding the TF:
Transcription unit        Promoter

Regulated gene(s) add, purD, purH, rbsA, rbsB, rbsC, rbsD, rbsK, rbsR
Multifun term(s) of regulated gene(s) MultiFun Term (List of genes associated to the multifun term)
carbon compounds (6)
nucleotide and nucleoside conversions (2)
purine biosynthesis (2)
ABC superfamily ATP binding cytoplasmic component (1)
ABC superfamily, periplasmic binding component (1)
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Regulated operon(s) add, purHD, rbsDACBKR
First gene in the operon(s) add, purH, rbsD
Simple and complex regulons CRP,RbsR
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
  RbsR-D-ribose activator addp6 Sigma70 -47.5 -78.5 add
1702145 1702164 [AIBSCS], [BPP], [GEA] [2]
  RbsR repressor purHp Sigma70 -20.5 -115.5 purH, purD
4207638 4207657 [AIBSCS], [BPP], [GEA] [2]
  RbsR repressor rbsDp Sigma70 8.5 -21.5 rbsD, rbsA, rbsC, rbsB, rbsK, rbsR
3933320 3933339 [AIBSCS], [BPP], [GEA] [1], [2]

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


 [BPP] Binding of purified proteins

 [IDA] Inferred from direct assay

 [IPI] Inferred from physical interaction

 [AIBSCS] Automated inference based on similarity to consensus sequences

 [GEA] Gene expression analysis


 [1] Mauzy CA., Hermodson MA., 1992, Structural and functional analyses of the repressor, RbsR, of the ribose operon of Escherichia coli., Protein Sci. 1(7):831-42

 [2] Shimada T., Kori A., Ishihama A., 2013, Involvement of the ribose operon repressor RbsR in regulation of purine nucleotide synthesis in Escherichia coli., FEMS Microbiol Lett. 344(2):159-65

 [3] Lopilato JE., Garwin JL., Emr SD., Silhavy TJ., Beckwith JR., 1984, D-ribose metabolism in Escherichia coli K-12: genetics, regulation, and transport., J Bacteriol. 158(2):665-73

 [4] Laikova ON., Mironov AA., Gelfand MS., 2001, Computational analysis of the transcriptional regulation of pentose utilization systems in the gamma subdivision of Proteobacteria., FEMS Microbiol Lett. 205(2):315-22

 [5] Bell AW., Buckel SD., Groarke JM., Hope JN., Kingsley DH., Hermodson MA., 1986, The nucleotide sequences of the rbsD, rbsA, and rbsC genes of Escherichia coli K12., J Biol Chem. 261(17):7652-8