Omics-based analysis of the luxS mutation in a clinical isolate of Escherichia coli O157:H7 in Korea.

The purpose of this study was to investigate the relationship between the global regulatory mechanism known as quorum sensing and expression of virulence factors in Escherichia coli O157:H7. A non-polar luxS deletion was introduced into the chromosome of strain CI03J, a human clinical isolate from South Korea, to create the DeltaluxS mutant strain ML03J. Phenotypic characterization of wild-type and mutant strains demonstrated that ML03J had no obvious growth or metabolic defects on 0.2% glucose LB medium, produced a functionally-defective flagellum, and could not utilize sorbose; the biological significance of sorbose utilization is unknown. Omics-based analysis revealed the involvement of LuxS in the transcriptional activation of several flagella/chemotaxis-related genes (flhD; fliA, C, D, S, Z; cheA, Y, and Z), repression of glutamate-dependent acid resistance genes (gadAB), and expression of virulence factors including Shiga toxin, hemolysin, and SepD within the LEE pathogenicity island.