Quorum sensing controls expression of the type III secretion gene transcription and protein secretion in enterohemorrhagic and enteropathogenic Escherichia coli

Abstract

Enterohemorrhagic Escherichia coli O157:H7 and enteropathogenic E. coli cause a characteristic histopathology in intestinal cells known as attaching and effacing. The attaching and effacing lesion is encoded by the Locus of Enterocyte Effacement (LEE) pathogenicity island, which encodes a type III secretion system, the intimin intestinal colonization factor, and the translocated intimin receptor protein that is translocated from the bacterium to the host epithelial cells. Using lacZ reporter gene fusions, we show that expression of the LEE operons encoding the type III secretion system, translocated intimin receptor, and intimin is regulated by quorum sensing in both enterohemorrhagic E. coli and enteropathogenic E. coli. The luxS gene recently shown to be responsible for production of autoinducer in the Vibrio harveyi and E. coli quorum-sensing systems is responsible for regulation of the LEE operons, as shown by the mutation and complementation of the luxS gene. Regulation of intestinal colonization factors by quorum sensing could play an important role in the pathogenesis of disease caused by these organisms. These results suggest that intestinal colonization by E. coli O157:H7, which has an unusually low infectious dose, could be induced by quorum sensing of signals produced by nonpathogenic E. coli of the normal intestinal flora.

Quorum sensing in bacterial virulence

“…Genetic studies in enterohaemorrhagic E. coli (EHEC) and enteropathogenic E. coli revealed that LuxS controls the expression of the type-3 secretion system encoded by the locus of enterocyte effacement (LEE) pathogenicity island (Sperandio et al, 1999). This important virulence determinant is required for the formation of the characteristic Quorum sensing in bacterial virulence -a review attaching and effacing (AE) lesions caused by these pathogens (Celli et al, 2000).…”

LsrR-binding site recognition and regulatory characteristics in Escherichia coli AI-2 quorum sensing

“…Subsequently, AI-2 production was verified in a large number of species and the AI-2 QS system was recognized to be involved in the regulation of a range of functions in diverse bacteria [6,7,10,[12][13][14]. In contrast to other autoinducers that are specific for a narrow range of organisms, the widely conserved AI-2 has been hypothesized to be a universal language for interspecies communication [6,9,10,13,15].…”

Integration host factor (IHF) mediates repression of flagella in enteropathogenic and enterohaemorrhagic Escherichia coli

“…Integration host factor (IHF) directly activates the expression of Ler (Friedberg et, al., 1999). Additional factors, including Fis, Per and a quorum sensing regulator, are also involved in the modulation of LEE1 expression (Goldberg et al, 2001;Kanamaru et al, 2000;Mellies et al, 1999;Sperandio et al, 1999Sperandio et al, , 2002a.…”