The present invention relates to the discovery of the lsr operon, the genes therein, and the polypeptides encoded by these genes. The present invention also includes strains with altered expression levels of the polypeptides encoded by the genes and the lsr operon relative to wild type cells. In some embodiments, the strains express a transporter that transports an autoinducer into the cell at a level higher than that of wild type cells. The present invention also includes methods for identifying compounds that modulate the transport of the autoinducer into cells.