Open AccessThe secreted autotransporter toxin, Sat, functions as a virulence factor in Afa/Dr diffusely adhering Escherichia coli by promoting lesions in tight junction of polarized epithelial cells
Author(s) -
Guignot Julie,
Chaplais Cécile,
CoconnierPolter MarieHélène,
Servin Alain L.
Publication year - 2007
Publication title -
cellular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.542
H-Index - 138
eISSN - 1462-5822
pISSN - 1462-5814
DOI - 10.1111/j.1462-5822.2006.00782.x
Subject(s) - biology , virulence , microbiology and biotechnology , bacterial adhesin , virulence factor , enterocyte , escherichia coli , tight junction , occludin , enterobacteriaceae , fimbria , recombinant dna , enterotoxigenic escherichia coli , gene , small intestine , genetics , enterotoxin , biochemistry
Summary Afa/Dr diffusely adhering Escherichia coli (DAEC) strains are responsible for urinary tract and intestinal infections. Both in intestine and kidney, the epithelial cells forming epithelium are sealed by junctional domains. We provide evidence that the S ecreted a utotransporter t oxin, Sat, belonging to the subfamily of serine protease autotransporters of Enterobacteriaceae (SPATEs), acts as a virulence factor in Afa/Dr DAEC by promoting lesions in the tight junctions (TJs) of polarized epithelial Caco‐2/TC7 cells. Southern blot analysis reveals that the prototype strains of the subclass‐1 and subclass‐2 typical Afa/Dr DAEC strains, hybridize with a sat probe. Using the wild‐type IH11128 strain, the recombinant E. coli AAEC185 strain that expresses Sat, the recombinant E. coli that expresses both Dr adhesin and Sat, we report that Sat in monolayers of cultured enterocyte‐like Caco‐2/TC7 cells, induces rearrangements of the TJs‐associated proteins ZO‐1, ZO‐3 and occludin, and increases the formation of domes as the result of an increase in the paracellular permeability without affecting the transepithelial electrical resistance of the cell monolayers. Moreover, we observe that Sat‐induced disassembly of TJs‐associated proteins is dependent on the serine protease motif. Finally, an analysis of the prevalence of the sat gene in three collections of Afa/Dr DAEC strains collected from the stools of children with and without diarrhoea, and from the urine of patients with urinary tract infection (UTI) shows that: (i) the sat gene is highly prevalent in UTI‐associated Afa/Dr DAEC strains (88% positive), (ii) the sat gene is generally absent from Afa/Dr DAEC strains collected from the stools of children without diarrhoea (16% positive); whereas (iii) it is present in about half of the strains collected from the stools of children with diarrhoea (46% positive).