Tails of two Tirs: actin pedestal formation by enteropathogenic E. coli and enterohemorrhagic E. coli O157:H7
Biochemistry & Molecular Pharmacology
Graduate School of Biomedical Sciences; Department of Molecular Genetics and Microbiology
Medical Subject Headings
Actins; Animals; Biological Transport; Escherichia coli; Escherichia coli O157; Escherichia coli Proteins; Humans; Oncogene Proteins; Receptors, Cell Surface; Signal Transduction
Life Sciences | Medicine and Health Sciences
Enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic E. coli O157:H7 (EHEC) form characteristic lesions on infected mammalian cells called actin pedestals. Each of these two pathogens injects its own translocated intimin receptor (Tir) molecule into the plasma membranes of host cells. Interaction of translocated Tir with the bacterial outer membrane protein intimin is required to trigger the assembly of actin into focused pedestals beneath bound bacteria. Despite similarities between the Tir molecules and the host components that associate with pedestals, recent work indicates that EPEC and EHEC Tir are not functionally interchangeable. For EPEC, Tir-mediated binding of Nck, a host adaptor protein implicated in actin signaling, is both necessary and sufficient to initiate actin assembly. In contrast, for EHEC, pedestals are formed independently of Nck, and require translocation of bacterial factors in addition to Tir to trigger actin signaling.
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Citation: Curr Opin Microbiol. 2003 Feb;6(1):82-90.