IGEM:IMPERIAL/2009/Encapsulation/Parts/Nonleakypromoter/

Target genes were cloned under control of the strong T7 promoter 

T7 RNA polymerase production was placed under control of the E.coli lac promoter

Low levels of T7 lysozyme supplied by plasmids pLysS or pLysL t7pol2 



The lower level of lysozyme provided by pLysS or pLysL has little effect on growth of the cell

Lysozyme binds to the T7 RNA polymerase present in the non-induced cell and prevents it from transcribing target genes, thereby avoiding the leaky expression of genes, which are under control of a T7 promoter

When the T7 RNA polymerase is induced,the production of RNA polymerase will exceed inhibition by lysozyme. Therefore, the T7 RNA polymerase will transcribe the target genes.

This has been used for expression of toxic malarial proteins in Escherichia coli t7pol1

Proposed application: Target genes= restriction enzymes

Useful references

 * 1) t7pol1 pmid=11606237


 * 1) t7pol2 pmid=2023259


 * 1) t7pol3 pmid=11080592