RegulonDB RegulonDB 9.4:Regulon Page

QseB DNA-binding transcriptional activator

Synonyms: QseB-Phosphorylated, QseB
QseB, quorum-sensing E. coli regulator B , is the response regulator component of the QseB-QseC two-component system, which is one component of the quorum-sensing regulatory cascade involved in the positive regulation of flagella and motility genes by activating transcription of flhDC, an operon that encodes the master regulator of these genes [2].
This protein also may have an undetermined role in metal metabolism, because qseBC deletion mutants show hypersensitivity to several toxic cations [5].
QseB and QseC of enterohemorrhagic E. coli (EHEC) and of E. coli K-12 are almost identical; there are only three amino acid differences in QseB and only eight amino acid differences in QseC between these strains [2]. It was demonstrated in EHEC that QseC directly senses and binds the bacterial hormone-like AI-3 signal and the host epineprhine/norepineprhine hormones, and it causes the autophosphorylation of QseC, which then transfers the phosphate group to QseB to activate it [1].
The expression of the operon containing both genes qseB, encoding the response regulator, and qseC, encoding the sensor kinase, is regulated by a quorum-sensing system [2], and the regulatory region of the operon is 99.6% identical to the regulatory region of the same operon in EHEC [4]. Read more >

Transcription factor      
TF conformation(s):
Name Conformation Type TF-Effector Interaction Type Apo/Holo Conformation Evidence (Confirmed, Strong, Weak) References
QseB Non-Functional   Apo [GEA], [IDA], [IEP], [IPI] [1]
QseB-Phosphorylated Functional Covalent Holo [GEA], [IDA], [IEP], [IPI] [1]
Evolutionary Family: OmpR
Sensing class: External-Two-component systems
Connectivity class: Local Regulator
Gene name: qseB
  Genome position: 3169828-3170487
  Length: 660 bp / 219 aa
Operon name: qseBC
TU(s) encoding the TF:
Transcription unit        Promoter

Regulated gene(s) flhC, flhD, qseB, qseC
Multifun term(s) of regulated gene(s) MultiFun Term (List of genes associated to the multifun term)
Transcription related (3)
activator (3)
flagellum (2)
repressor (2)
operon (2)
Read more >
Regulated operon(s) flhDC, qseBC
First gene in the operon(s) flhD, qseB
Simple and complex regulons AcrR,CRP,FliZ,Fur,H-NS,HdfR,IHF,LrhA,MatA,OmpR,QseB,RcsB,YjjQ
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
  QseB-Phosphorylated activator flhDp Sigma70 nd nd flhD, flhC nd nd [GEA] [2]
  QseB-Phosphorylated activator qseBp2 Sigma70 -462.0 -541.0 qseB, qseC
3169281 3169293 [BPP], [GEA] [3], [4]
  QseB-Phosphorylated activator qseBp2 Sigma70 6.0 -74.0 qseB, qseC
3169748 3169760 [BPP], [GEA] [3], [4]

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


 [GEA] Gene expression analysis

 [IDA] Inferred from direct assay

 [IEP] Inferred from expression pattern

 [IPI] Inferred from physical interaction

 [BPP] Binding of purified proteins


 [1] Clarke MB., Hughes DT., Zhu C., Boedeker EC., Sperandio V., 2006, The QseC sensor kinase: a bacterial adrenergic receptor., Proc Natl Acad Sci U S A. 103(27):10420-5

 [2] Sperandio V., Torres AG., Kaper JB., 2002, Quorum sensing Escherichia coli regulators B and C (QseBC): a novel two-component regulatory system involved in the regulation of flagella and motility by quorum sensing in E. coli., Mol Microbiol. 43(3):809-21

 [3] Clarke MB., Sperandio V., 2005, Transcriptional regulation of flhDC by QseBC and sigma (FliA) in enterohaemorrhagic Escherichia coli., Mol Microbiol. 57(6):1734-49

 [4] Clarke MB., Sperandio V., 2005, Transcriptional autoregulation by quorum sensing Escherichia coli regulators B and C (QseBC) in enterohaemorrhagic E. coli (EHEC)., Mol Microbiol. 58(2):441-55

 [5] Zhou L., Lei XH., Bochner BR., Wanner BL., 2003, Phenotype microarray analysis of Escherichia coli K-12 mutants with deletions of all two-component systems., J Bacteriol. 185(16):4956-72