Disease relevance of ECs4556

• Two enteropathogenic Escherichia coli type III secreted proteins, EspA and EspB, are virulence factors [1].
• Although the mutation had no effect on EspA filament biosynthesis, it also resulted in reduced binding to and reduced hemolysis of red blood cells [2].

High impact information on ECs4556

• The virulence of EspA and EspB mutant strains was severely attenuated [1].
• Here, we describe a novel EspA-containing filamentous organelle that is present on the bacterial surface during the early stage of A/E lesion formation, forms a physical bridge between the bacterium and the infected eukaryotic cell surface and is required for the translocation of EspB into infected epithelial cells [3].
• A novel EspA-associated surface organelle of enteropathogenic Escherichia coli involved in protein translocation into epithelial cells [3].
• Non-conservative amino acid substitution of specific EspA heptad residues generated EPEC mutants defective in filament assembly but which retained the ability to induce A/E lesions; additional mutation totally abolished EspA filament assembly and A/E lesion formation [4].
• This control in E. coli O157:H7 may be required to limit exposure of key surface antigens, EspA, Tir and intimin during colonization of cattle but allow their rapid production on contact with bovine gastrointestinal epithelium at the terminal rectum [5].

Chemical compound and disease context of ECs4556

• EspA filaments could not be detected on the bacterial cell surface when E. coli O157:H7 was cultured in M9 minimal medium but were expressed from only a proportion of the bacterial population when cultured in minimal essential medium modified with 25 mM HEPES [6].

Biological context of ECs4556

• As for the flagellin D3 domain, which is known to tolerate insertions of natural and artificial amino acid sequences, we have inserted short peptides into the surface-exposed, hypervariable domain of EspA [7].
• The ability of individual bacteria to express EspA filaments was not controlled at the level of LEE1-4 operon transcription, as demonstrated by using both beta-galactosidase and green fluorescent protein (GFP) promoter fusions [6].
• One set is dependent on EPEC proteins secreted by the type III secretion pathway (EspA and EspB) which induces Hp90 tyrosine phosphorylation and dephosphorylation of host phosphotyrosine proteins [8].
• The EPEC antiphagocytic phenotype was dependent on the type III secretion pathway of EPEC and its secreted proteins, including EspA, EspB, and EspD [9].
• This cell cycle inhibition by E22 was abrogated in mutants lacking EspA, -B, and -D and was restored by transcomplementation [10].

Anatomical context of ECs4556

• Nevertheless, binding of EspA filaments to the host cell membranes occurred even in the absence of EspB [11].
• Here, we describe a novel EspA-containing filamentous organelle that is present on the bacterial surface during the early stage of A/E lesion formation, forms a physical bridge between the bacterium and the infected eukaryotic cell surface and is required for the translocation of EspB into infected epithelial cells [12].
• We found that some DAEC strains contain homologues of the locus of enterocyte effacement (LEE) pathogenicity island and secrete EspA, EspB and EspD proteins necessary for the formation of the attaching and effacing (A/E) lesions [13].
• EspA was detected in often filament-like structures decorating all bacteria that had attached to HeLa cells [14].
• EspA forms a filamentous structure on the bacterial cell surface and is involved in translocation of proteins into the eukaryotic cytosol [15].

Associations of ECs4556 with chemical compounds

• As EspA filaments link bacteria and the host cell, we predicted that intimate bacteria-RBC contact would not be required for EPEC-induced haemolysis and, therefore, in this study we investigated the interaction of EPEC with monolayers of RBCs attached to polylysine-coated cell culture dishes [16].
• This mutant is incapable of attaching and effacing, of secreting EspA and EspB and of inducing tyrosine phosphorylation of host cell proteins [17].
• EHEC grown with either TMAO or nitrate possessed a more intact type III secretion (TTS) apparatus, including the needle protein EscF and the translocator protein EspA, than EHEC grown without an electron acceptor [18].
• Interestingly, urea-induced unfolding transitions, monitored by far-UV CD spectroscopy, showed that the protein is destabilized at pH 2.0 as compared with EspA at neutral pH [19].

Analytical, diagnostic and therapeutic context of ECs4556

• Furthermore, the transmission electron microscopy view with immunogold labeled anti-EspA antibodies clearly showed that EspA is a component of the sheath-like structure [20].
• By immunofluorescence, a polyclonal antibody previously raised to EspA from EPEC strain E2348/69 (O127:H6) stained approximately 12-nm-diameter EspA filaments produced by this strain but did not stain similar filaments produced by EHEC serotype O157:H7 [21].
• The results of analytical ultracentrifugation and infrared spectroscopy indicate that EspA molecules associate at pH 7.0, suggesting the formation of short filamentous oligomers containing alpha-helical structures, whereas the protein tend to form nonspecific aggregates containing intermolecular beta-sheets at pH 2 [19].

References