Part:BBa_K364325

Gal4-PXR

Gal4 DBD - human Pregnane X receptor

Artificial eukaryotic TF made of Gal4 DBD (DNA Binding Domain) and H. sapiens nuclear hormone receptor LBD (Ligand Binding Domain)

PXR LBD

PXR is a xenobiotic-activated member of the nuclear receptor superfamily of transcription factors. PXR is involved in transcriptional induction of hepatic xenobiotic-catabolizing cytochrome 3A enzymes, playing a fundamental role in protecting body tissues from toxic bile acids. PXR is almost exlcusively expressed in the gastrointestinal system (stomach, duodenum, jejunum, ileum, colon and gall bladder) and liver, with lower levels in the kidney and ovary. PXR dysfunction is associated with immune disorders (sclerosing cholangitis, inflammatory bowel disease) and biliary primary cirrhosis.

Gal4 DBD

This protein is a positive regulator for the gene expression of the galactose-induced genes such as GAL1, GAL2, GAL7, GAL10, and MEL1 which encode for the enzymes used to convert galactose to glucose. This protein contains a fungal Zn(2)-Cys(6) binuclear cluster domain.

This composite artificial transcription factor will activate any reporter or any gene in general that has a UAS (Upper Activating Sequence) 3' of it's promoter. The usual binding sites of reporters, contain multiple UAS elements. In order to have a POPS output, the LBD has to recruit activators in the cell. This can be initiated by ligand binding or by recruiting a protein that has a fused strong activator like the VP activator.

With this system NHR (Nuclear Hormone Receptor) ligands or NHR interacting partners can be screened.

The NHR: cofactor-VP interaction should be also broken by a potential ligand binding, this is why this setup is also suitable for ligand identification. The benefit of the cofactor-VP interaction test is that the dynamic range of the assay is much higher than the dynamic range of the normal Gal4-NHR ligand activation assay.

More info about this project on the wiki pages of Team Debrecen-Hungary 2010. [http://2010.igem.org/Team:Debrecen-Hungary]

Picture of gel electrophoresis: Gal4-PXR in pSB1C3 resulting an insert of 1181 bp. The restricted pSB1C3-RFP have been added on the gel as a control of the backbone.

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  COMPATIBLE WITH RFC[12]
• 21
  INCOMPATIBLE WITH RFC[21]

  Illegal BglII site found at 583
  Illegal BglII site found at 694
  Illegal BamHI site found at 1117
  Illegal XhoI site found at 218
  
• 23
  COMPATIBLE WITH RFC[23]
• 25
  COMPATIBLE WITH RFC[25]
• 1000
  INCOMPATIBLE WITH RFC[1000]

  Illegal BsaI site found at 137