Description

This promoter is composed by phage T5 promoter and Lac operator. It is repressed in the presence of the lac repressor protein and activated in the presence of IPTG which binds the repressor inactivating it.

Assembly

Obtained by synthesis.

Results

Trieste Team 2012 used this inducible promoter in the first phase of their project to test every construct that could have been toxic for the host strain, if expressed in a constitutive way.

FIG. 1. Expression of LPP-OmpA-scFv 54.6 cloned under T5Lac Operator. Western blots of lysates of E.coli W3110 bacterial strain expressing the recombinant protein scFv 54.6, induced or non-induced with IPTG.The blot was reacted with the monoclonal F24-796 anti-6XHIS antibody.

How it works:
The host strain contains the low copy plasmid pREP4 which constitutively expresses the Lac repressor protein encoded by the LacI gene. The Lac repressor binds the operator sequence preventing the transcription. The Lac repressor protein is rapidly inactivated by the binding of isopropyl-β-thiogalactoside (IPTG).

We also tested the T5Lac Operator Promoter cloned upstream the Tse2 toxin construct. And this is the growth curve of IPTG induced and non-induced cells:

Link to the Registry