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BetI DNA-binding transcriptional repressor

Synonyms: BetI, BetI-choline
Summary:
Betaine inhibitor, BetI, acts as a repressor of glycine betaine synthesis from choline [2] It is negatively autoregulated and coordinately represses transcription of the choline transporter and the operon related to the synthesis of glycine betaine. These divergent operons are expressed only under aerobic conditions and are induced by osmotic stress [3]
BetI is an unusual repressor because it remains bound to DNA during induction. BetI forms a complex with DNA in the presence of choline, binding to a 20-bp-long sequence with dyad symmetry that overlaps betTp and betIp simultaneously [1] The position of the repressor gene within the operon is unusual too, as regulatory genes tend to be positioned at the end of operons and this gene is located at the beginning of the operon.
BetI belongs to the TetR/AcrR family of transcriptional regulators [1, 3] This protein composed of two domains, an amino-terminal domain that contains a potential helix-turn-helix DNA-binding motif and a carboxy-terminal domain involved in co-inducer recognition and dimerization [3]. Read more >


Transcription factor      
TF conformation(s):
Name Conformation Type TF-Effector Interaction Type Apo/Holo Conformation Evidence (Confirmed, Strong, Weak) References
BetI Functional   Apo [BPP], [GEA] [1]
BetI-choline Non-Functional Allosteric Holo [BPP], [GEA] [1]
Evolutionary Family: TetR/AcrR
Sensing class: External sensing using transported metabolites
Connectivity class: Local Regulator
Gene name: betI
  Genome position: 328747-329334
  Length: 588 bp / 195 aa
Operon name: betIBA
TU(s) encoding the TF:
Transcription unit        Promoter
betIBA
betIp


Regulon       
Regulated gene(s) betA, betB, betI, betT
Multifun term(s) of regulated gene(s) MultiFun Term (List of genes associated to the multifun term)
betaine biosynthesis (3)
osmotic pressure (3)
membrane (2)
Transcription related (1)
repressor (1)
Read more >
Regulated operon(s) betIBA, betT
First gene in the operon(s) betI, betT
Simple and complex regulons ArcA,BetI,Cra
Simple and complex regulatory phrases Regulatory phrase (List of promoters regulated by the phrase)
[BetI,-](2)


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
  BetI repressor betIp Sigma70 -30.0 -56.5 betI, betB, betA
agacacatttTATATTGAACGTCCAATCAAtaaccgcttt
329381 329400 [GEA], [HIBSCS] [1], [2]
  BetI repressor betTp Sigma70 -30.0 -72.5 betT
aaagcggttaTTGATTGGACGTTCAATATAaaatgtgtct
329381 329400 [GEA], [HIBSCS] [1], [2]


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


Evidence    

 [BPP] Binding of purified proteins

 [GEA] Gene expression analysis

 [HIBSCS] Human inference based on similarity to consensus sequences



Reference(s)    

 [1] Rkenes TP., Lamark T., Strom AR., 1996, DNA-binding properties of the BetI repressor protein of Escherichia coli: the inducer choline stimulates BetI-DNA complex formation., J Bacteriol. 178(6):1663-70

 [2] Lamark T., Rokenes TP., McDougall J., Strom AR., 1996, The complex bet promoters of Escherichia coli: regulation by oxygen (ArcA), choline (BetI), and osmotic stress., J Bacteriol. 178(6):1655-62

 [3] Lamark T., Kaasen I., Eshoo MW., Falkenberg P., McDougall J., Strom AR., 1991, DNA sequence and analysis of the bet genes encoding the osmoregulatory choline-glycine betaine pathway of Escherichia coli., Mol Microbiol. 5(5):1049-64



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