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EbgR DNA-binding transcriptional repressor

Synonyms: EbgR
EbgR (for "evolved β-galactosidase repressor") negatively regulates genes involved in the evolved β-galactosidase system, which constitutes an alternative for lactose utilization in cells with mutations on the lacZ gene [2, 3]. The wild-type Ebg enzyme, encoded by the ebg operon, is not efficient enough to permit growth on lactose. Mutations in ebgR and ebgA, however, enhance its catalytic activity and enable rapid growth on lactose as a sole carbon source [2, 3]. EbgR belongs to the GalR-LacI family of transcriptional regulators. There is strong evidence that the ebg and lac operons share a common origin in evolution [2]. EbgR diverged from other repressors shortly after the divergence of the Gram positive from the Gram negative eubacteria, approximately 2.2 billion years ago [4] Reviews: [3, 4] Read more >

Transcription factor      
TF conformation(s):
Name Conformation Type TF-Effector Interaction Type Apo/Holo Conformation Evidence (Confirmed, Strong, Weak) References
EbgR Functional   [IE] nd
Evolutionary Family: GalR/LacI
Connectivity class: Local Regulator
Gene name: ebgR
  Genome position: 3221466-3222449
  Length: 984 bp / 327 aa
Operon name: ebgR
TU(s) encoding the TF:
Transcription unit        Promoter

Regulated gene(s) ebgA, ebgC
Multifun term(s) of regulated gene(s)
carbon compounds (2)
Regulated operon(s) ebgAC
First gene in the operon(s) ebgA
Simple and complex regulons CRP,EbgR
Simple and complex regulatory phrases Regulatory phrase (List of promoters regulated by the phrase)

Transcription factor regulation    

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
  EbgR repressor ebgAp Sigma70 nd nd ebgA, ebgC nd nd [GEA] [1]

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


 [IE] Inferred from experiment

 [GEA] Gene expression analysis


 [1] Hall BG., Betts PW., Wootton JC., 1989, DNA sequence analysis of artificially evolved ebg enzyme and ebg repressor genes., Genetics 123(4):635-48

 [2] Stokes HW, Hall BG, 1985, Sequence of the ebgR gene of Escherichia coli: evidence that the EBG and LAC operons are descended from a common ancestor., Mol Biol Evol, 1985 Nov

 [3] Hall BG, 1999, Experimental evolution of Ebg enzyme provides clues about the evolution of catalysis and to evolutionary potential., FEMS Microbiol Lett, 1999 May 1

 [4] Hall BG, 2003, The EBG system of E. coli: origin and evolution of a novel beta-galactosidase for the metabolism of lactose., Genetica, 2003 Jul