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CadC DNA-binding transcriptional activator

Synonyms: CadC
CadC is a metal-sensitive transcriptional activator that regulates the expression of genes involved in cadaverine synthesis and excretion under low external pH and high concentrations of lysine [3, 4]. Two binding sites for CadC, Cad1 and Cad2, have been determined in the cadBA operon. While Cad1 contains an inverted repeat sequence and has a preference for AT-rich regions [], Cad2 lacks either an inverted repeat or a palindromic sequence. Both binding sites are necessary for cadBA activation. Under aerobic conditions, H-NS represses the cadBA operon. Upon binding to Cad1, CadC releases bound H-NS molecules, dissolving the H-NS repressor complex and allowing RNA polymerase binding. Transcription of cadBA is finally activated once a molecule of CadC binds to Cad2 [4]. CadC is an integral membrane protein that belongs to the ToxR-like family of transcriptional activators. It features a cytoplasmic DNA-binding N-terminal domain, a transmembrane domain, and a periplasmic C-terminal domain [4].
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Transcription factor      
TF conformation(s):
Name Conformation Type TF-Effector Interaction Type Apo/Holo Conformation Evidence (Confirmed, Strong, Weak) References
CadC Functional   [IMP] [1], [2], [3]
Evolutionary Family: OmpR
Sensing class: External sensing using transported metabolites
Connectivity class: Local Regulator
Gene name: cadC
  Genome position: 4360396-4361934
  Length: 1539 bp / 512 aa
Operon name: cadC
TU(s) encoding the TF:
Transcription unit        Promoter

Regulated gene(s) cadA, cadB, cadC
Multifun term(s) of regulated gene(s) MultiFun Term (List of genes associated to the multifun term)
pH (1)
Porters (Uni-, Sym- and Antiporters) (1)
membrane (1)
amino acids (1)
Transcription related (1)
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Regulated operon(s) cadBA, cadC
First gene in the operon(s) cadB, cadC
Simple and complex regulons ArcA,CadC,GadE-RcsB,GadX,H-NS,Lrp
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
  CadC activator cadBp Sigma70 nd 4360031.0 cadB, cadA nd nd [BPP], [GEA] [3], [4]
  CadC activator cadCp Sigma70 nd 4361934.0 cadC nd nd [GEA] [3]

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


 [IMP] Inferred from mutant phenotype

 [BPP] Binding of purified proteins

 [GEA] Gene expression analysis


 [1] Dell CL., Neely MN., Olson ER., 1994, Altered pH and lysine signalling mutants of cadC, a gene encoding a membrane-bound transcriptional activator of the Escherichia coli cadBA operon., Mol Microbiol 14(1):7-16

 [2] Tetsch L., Koller C., Haneburger I., Jung K., 2008, The membrane-integrated transcriptional activator CadC of Escherichia coli senses lysine indirectly via the interaction with the lysine permease LysP., Mol Microbiol 67(3):570-83

 [3] Watson N., Dunyak DS., Rosey EL., Slonczewski JL., Olson ER., 1992, Identification of elements involved in transcriptional regulation of the Escherichia coli cad operon by external pH., J Bacteriol 174(2):530-40

 [4] Kuper C., Jung K., 2005, CadC-mediated activation of the cadBA promoter in Escherichia coli., J Mol Microbiol Biotechnol 10(1):26-39

 [5] Buchner S., Schlundt A., Lassak J., Sattler M., Jung K., 2015, Structural and Functional Analysis of the Signal-Transducing Linker in the pH-Responsive One-Component System CadC of Escherichia coli., J Mol Biol 427(15):2548-61

 [6] Rauschmeier M., Schuppel V., Tetsch L., Jung K., 2014, New insights into the interplay between the lysine transporter LysP and the pH sensor CadC in Escherichia coli., J Mol Biol 426(1):215-29