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Enterohemorrhagic Escherichia coli (EHEC) is a major cause of foodborne gastrointestinal illness. EHEC uses a specialized type III secretion system (T3SS) to form attaching and effacing lesions in the colonic epithelium and outcompete commensal gut microbiota to cause disease., Enterohemorrhagic Escherichia coli (EHEC) is a major cause of foodborne gastrointestinal illness. EHEC uses a specialized type III secretion system (T3SS) to form attaching and effacing lesions in the colonic epithelium and outcompete commensal gut microbiota to cause disease. A recent report in mBio (E. A. Cameron, M. M. Curtis, A. Kumar, G. M. Dunny, et al., mBio 9:e02204-18, 2018, https://doi.org/10.1128/mBio.02204-18) describes a new role for gut commensals in potentiating disease caused by EHEC. Proteases produced by EHEC and the prevalent human commensal Bacteroides thetaiotaomicron cleave proteins in the EHEC T3SS translocon that modulate T3SS function. B. thetaiotaomicron protease activity promotes translocation of bacterial effectors required for lesion formation. These results describe a new role for the microbiota in gastrointestinal disease that could uncover future treatments to prevent the spread of gastroenteritis.

Enterohemorrhagic E. coli (EHEC) causes severe diseases in humans worldwide. One of its virulence factors is EspP, which belongs to the serine protease autotransporters of Enterobacteriaceae (SPATE) family. In this review we recapitulate the current data on prevalence, biogenesis, structural properties and functionality. EspP has been used to investigate mechanistic details of autotransport, and recent studies indicate that this transport mechanism is not autonomous but rather dependent on additional factors. Currently, five subtypes have been identified (EspPα-EspPε), with EspPα being associated with highly virulent EHEC serotypes and isolates from patients with severe disease. EspPα has been shown to degrade major proteins of the complement cascade, namely C3 and C5 and probably interferes with hemostasis by cleavage of coagulation factor V. Furthermore, EspPα is believed to contribute to biofilm formation perhaps by polymerization to rope-like structures. Together with the proteolytic activity, EspPα might ameliorate host colonization and interfere with host response.

Die große Spanne der klinischen Ausprägungen von Infektionen mit Shiga Toxin-produzierenden E. coli-Stämmen (STEC) deutet darauf hin, dass neben dem Hauptvirulenzfaktor Shiga Toxin (Stx) weitere Determinanten Einfluss auf die Pathogenität der verschiedenen STEC-Stämme haben. Ein potenzieller Virulenzfaktor ist die in hochvirulenten Serogruppen weit verbreitete extrazelluläre Serinprotease EspP. Ziel dieser Arbeit war es, bei hochvirulenten EHEC-Stämmen die genetische Variation der espP-Gene zu analysieren und der EspP-Aktivität und Funktionalität gegenüberzustellen. Mittels Restriktionsanalysen konnten geringe Serogruppen-spezifische Unterschiede des espP-Gens nachgewiesen werden. Im zweiten Teil konnte gezeigt werden, dass diese genetischen Heterogenitäten keine Auswirkung auf die Autotransporter-Funktion oder die proteolytische Aktivität von EspP hatten. Hierdurch wurde gezeigt, dass espP in den untersuchten hochvirulenten EHEC-Serogruppen stark konserviert ist.

We compared PCR amplification of 9 enterohemorrhagic Escherichia coli virulence factors among 40 isolates (21 O/H antigenicity classes) with DNA hybridization. Both methods showed 100% of the chromosomal and phage genes: eae, stx, and stx2. PCR did not detect 4%–20% of hybridizable plasmid genes: hlyA, katP, espP, toxB, open reading frame (ORF) 1, and ORF2.