Regulatory

Part:BBa_K190023

Designed by: Michael Verhoeven   Group: iGEM09_Groningen   (2009-08-25)

Arsenic Promoter (ArsR regulated) with own RBS

Promoter sequence containing the recognition site for ArsR transcriptional regulator protein. Downstream from the promoter is the RBS that is attached to this promoter region in the E. coli genome. ArsR binds to the promoter sequence in the absence of As and releases on binding of As, thereby activating transcription (1).

Sequence and Features


Assembly Compatibility:
  • 10
    COMPATIBLE WITH RFC[10]
  • 12
    COMPATIBLE WITH RFC[12]
  • 21
    COMPATIBLE WITH RFC[21]
  • 23
    COMPATIBLE WITH RFC[23]
  • 25
    COMPATIBLE WITH RFC[25]
  • 1000
    COMPATIBLE WITH RFC[1000]

Promoter arsRp is associated with the dimer of ArsR for the arsenic induced transcription of genes involved in arsenic efflux (arsR, arsB and arsC, which is present on the genome of Escherichia coli str. K-12 substrain MG1655). The sequence shows the typical -10 and -35 region of the promoter and can be found through the following link. A second region, located at -41.5 from the transcription start site, is thought to bind dimeric ArsR. Upon binding of arsenic, the dimer dissociates and allows the RNA polymerase space to attach itself, and can also be found in the same link.

  • ArsR belongs to the ArsR/SmtB family of transcriptional regulators that respond to a variety of metals. ArsR has a helix-turn-helix motif for DNA binding, a metal-binding site, and a dimerization domain. In ArsR the inducer-binding site contains three cysteine residues that bind arsenite and antimonite specifically and with high affinity. Dimerization of ArsR is required for DNA binding and its ability to act as a transcriptional repressor. The dimer recognizes and binds to a 12-2-12 inverted repeat, but the binding of arsenic or antimonite to ArsR causes a conformational change in it, leading to dissociation from DNA and hence derepression (KEGG).
  • ArsR negatively controls the expression of the genes involved in arsenical and antimone metals resistance, whose expression is induced in the presence of these metals. The protein is autoregulated, because arsR is the first gene in the arsRBC operon that it regulates. Overexpression of ArsR in Escherichia coli has been used for removal of arsenite from contaminated water (KEGG).
(ArsR)2-DNA → ArsR-Ar + ArsR-Ar + DNA → Activation of transription

The presence of all genes and promoters on the chromosome of E. coli makes the use of the arsRp for induction of the GVP cluster relatively straith forward.


[edit]
Categories
//function/regulation/transcriptional
//promoter
//regulation/negative
Parameters
control
negative_regulators