Protein expression enhancement in efflux-deleted mutant bacteria.

We applied a single-cell assay to characterize how transcription dynamics affects protein expression levels of a tetracycline-inducible gene expression system. Transcriptional activity of the tetracycline promoter in response to a steady level of inducer is steady in DeltaacrAB efflux mutant but pulsating in wildtype Escherichia coli cells. We found that the expression level of the green fluorescent protein is several folds higher in DeltaacrAB efflux mutant than in wildtype cells.