Regulation of an antibiotic resistance efflux pump by quorum sensing and a TetR-family repressor in Chromobacterium subtsugae .

Many bacteria regulate antibiotic resistance in response to antibiotics and other cues from the environment. In many cases the regulatory mechanisms are best understood in the context of clinical isolates where mutations frequently emerge in resistance regulation pathways. However, an understanding of the role of antibiotic resistance regulators in integrating environmental information is less well understood. In the soil bacterium an antibiotic-resistance gene cluster is regulated by population density and antibiotics through two different transcription factors; the quorum sensing signal receptor CviR and an antibiotic-responsive transcription factor CdeR. In this study, we show that these factors independently modulate the transcription of the antibiotic resistance genes and coordinate to ensure sensitive responses to changes in cell density. The results give new insight into antibiotic resistance regulation in and contribute to a broader understanding of how bacteria optimize the regulation of antibiotic resistance in response to changes in the environment.