title: Role of intimin-tir interactions and the tir-cytoskeleton coupling protein in the colonization of calves and lambs by Escherichia coli O157:H7.
abstract: Intimin facilitates intestinal colonization by enterohemorrhagic Escherichia coli O157:H7; however, the importance of intimin binding to its translocated receptor (Tir) as opposed to cellular coreceptors is unknown. The intimin-Tir interaction is needed for optimal actin assembly under adherent bacteria in vitro, a process which requires the Tir-cytoskeleton coupling protein (TccP/EspF(U)) in E. coli O157:H7. Here we report that E. coli O157:H7 tir mutants are at least as attenuated as isogenic eae mutants in calves and lambs, implying that the role of intimin in the colonization of reservoir hosts can be explained largely by its binding to Tir. Mutation of tccP uncoupled actin assembly from the intimin-Tir-mediated adherence of E. coli O157:H7 in vitro but did not impair intestinal colonization in calves and lambs, implying that pedestal formation may not be necessary for persistence. However, an E. coli O157:H7 tccP mutant induced typical attaching and effacing lesions in a bovine ligated ileal loop model of infection, suggesting that TccP-independent mechanisms of actin assembly may operate in vivo.
authors.affiliation: Institute for Animal Health, High Street, Compton, Berkshire RG20 7NN, United Kingdom.
authors.forename: Isabella
authors.initials: I
authors.lastname: Vlisidou
authors.forename: Francis
authors.initials: F
authors.lastname: Dziva
authors.forename: Roberto M
authors.initials: RM
authors.lastname: La Ragione
authors.forename: Angus
authors.initials: A
authors.lastname: Best
authors.forename: Junkal
authors.initials: J
authors.lastname: Garmendia
authors.forename: Pippa
authors.initials: P
authors.lastname: Hawes
authors.forename: Paul
authors.initials: P
authors.lastname: Monaghan
authors.forename: Shaun A
authors.initials: SA
authors.lastname: Cawthraw
authors.forename: Gad
authors.initials: G
authors.lastname: Frankel
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Woodward
authors.forename: Mark P
authors.initials: MP
authors.lastname: Stevens
mesh_terms: D018829:Adhesins, Bacterial / Q000378:metabolism*; D000818:Animals; D002417:Cattle; D003599:Cytoskeleton / Q000378:metabolism* / Q000382:microbiology*; D019453:Escherichia coli O157 / Q000254:growth & development* / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D005243:Feces / Q000382:microbiology; D006367:HeLa Cells; D006801:Humans; D011956:Receptors, Cell Surface / Q000378:metabolism*; D012756:Sheep; D012757:Sheep Diseases / Q000382:microbiology* / Q000473:pathology
chemical_list: D018829:Adhesins, Bacterial; D029968:Escherichia coli Proteins; D011956:Receptors, Cell Surface; C109287:Tir protein, E coli; C505370:tccP protein, E coli; C073819:eaeA protein, E coli