Enterohaemorrhagic Escherichia coli (EHEC) O157:H7 causes gastrointestinal disease with the potential for life-threatening sequelae. Although Shiga-like toxins are responsible for much of the serious pathology in humans, the bacterium also possesses a type III protein secretion system that is responsible for intimate attachment to host intestinal mucosa. This sophisticated interaction requires co-ordination that is governed by environmental and genetic factors. Ongoing research supports the following model for how EHEC enables and controls this process: (i) specific environmental cues that are present in the host result in the expression of a number of adhesins, including fimbriae, which allow the initial binding to the mucosal surface. The same conditions support the expression of the basal type III secretion apparatus; (ii) targeting and assembly of the translocon requires both an mRNA signal and chaperones, with coupled translation and secretion of translocon proteins, EspA, B and D; (iii) opening up of a conduit between the bacterium and host cell releases a cytoplasmic pool of effector proteins. A consequence of this is increased expression of particular effector proteins. Potentially, different proteins could be released into the cell at different times or have activities modulated with time; (iv) intimate contact between the translocated intimin receptor (Tir) and the bacterial surface factor intimin requires translocon expression to be down-regulated and translocon filaments to be lost. Fluorescent protein fusions allow contact-mediated regulation and protein targeting through the type III secretion system to be studied in detail.
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February 2003
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Conference Article|
February 01 2003
Regulation, secretion and activity of type III-secreted proteins of enterohaemorrhagic Escherichia coli O157
A.J. Roe;
A.J. Roe
Zoonotic and Animal Pathogens Research Laboratory, Medical Microbiology, Teviot Place, University of Edinburgh, Edinburgh EH8 9AG, U.K.
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D.E.E. Hoey;
D.E.E. Hoey
Zoonotic and Animal Pathogens Research Laboratory, Medical Microbiology, Teviot Place, University of Edinburgh, Edinburgh EH8 9AG, U.K.
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D.L. Gally
D.L. Gally
1
Zoonotic and Animal Pathogens Research Laboratory, Medical Microbiology, Teviot Place, University of Edinburgh, Edinburgh EH8 9AG, U.K.
1To whom correspondence should be addressed (e-mail d.gally@ed.ac.uk)
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Publisher: Portland Press Ltd
Online ISSN: 1470-8752
Print ISSN: 0300-5127
Copyright 2003 Biochemical Society
2003
Biochem Soc Trans (2003) 31 (1): 98–103.
Citation
A.J. Roe, D.E.E. Hoey, D.L. Gally; Regulation, secretion and activity of type III-secreted proteins of enterohaemorrhagic Escherichia coli O157. Biochem Soc Trans 1 February 2003; 31 (1): 98–103. doi: https://doi.org/10.1042/bst0310098
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