A novel, inducible, eukaryotic gene expression system based on the quorum‐sensing transcription factor TraR

Bacteria adapt their pattern of gene expression in response to a variety of external cues, including fluctuations in population density. This type of bacterial cell‐to‐cell communication is referred to as quorum‐sensing. Quorum‐sensing systems are present in many bacterial species and constitute a large collection of ligands and cognate receptors. The availability of such diversity offers interesting opportunities for biotechnological exploitation. We describe here the transformation of the quorum‐sensing system of Agrobacterium tumefaciens into a transcription regulatory system that works in mammalian cells. The A. tumefaciens TraR protein was fused to the eukaryotic activation domain of NF‐κB p65, generating a novel chimaeric transcriptional activator that stimulates gene transcription in different human cell lines from a minimal promoter containing the TraR DNA recognition sequence in the presence of the Agrobacterium quorum‐sensing signal molecule N‐(3‐oxo‐octanoyl)homoserine lactone (3‐oxo‐C8‐HSL). The basal level of transcription was low in the absence of 3‐oxo‐C8‐HSL, and gene expression was stimulated up to 1,000‐fold at a saturating concentration of 3‐oxo‐C8‐HSL.

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