Co‐ordinate single‐cell expression of LEE4‐ and LEE5‐encoded proteins of Escherichia coli O157:H7

Summary Escherichia coli O157:H7 is a zoonotic pathogen that can express a type III secretion system (TTSS) considered important for colonization and persistence in ruminants. E. coli O157:H7 strains have been shown to vary markedly in levels of protein secreted using the TTSS and this study has con...

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Published in:	Molecular microbiology Vol. 54; no. 2; pp. 337 - 352
Main Authors:	Roe, Andrew J., Naylor, Stuart W., Spears, Kevin J., Yull, Helen M., Dransfield, Tracy A., Oxford, Matthew, McKendrick, Iain J., Porter, Megan, Woodward, Martin J., Smith, David G. E., Gally, David L.
Format:	Journal Article
Language:	English
Published:	Oxford, UK Blackwell Science Ltd 01-10-2004 Blackwell Science Blackwell Publishing Ltd
Subjects:	Adhesins, Bacterial - genetics Adhesins, Bacterial - metabolism Animals Bacteriology Biological and medical sciences Cattle Cells, Cultured Escherichia coli Escherichia coli O157 - cytology Escherichia coli O157 - genetics Escherichia coli O157 - metabolism Escherichia coli O157 - pathogenicity Escherichia coli Proteins - genetics Escherichia coli Proteins - metabolism Fundamental and applied biological sciences. Psychology Humans Microbiology Miscellaneous Phosphoproteins - genetics Phosphoproteins - metabolism Receptors, Cell Surface - genetics Receptors, Cell Surface - metabolism Recombinant Fusion Proteins - genetics Recombinant Fusion Proteins - metabolism Bacteria Microbiology Escherichia coli Protein Enterobacteriaceae
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Summary:	Summary Escherichia coli O157:H7 is a zoonotic pathogen that can express a type III secretion system (TTSS) considered important for colonization and persistence in ruminants. E. coli O157:H7 strains have been shown to vary markedly in levels of protein secreted using the TTSS and this study has confirmed that a high secretion phenotype is more prevalent among isolates associated with human disease than isolates shed by healthy cattle. The variation in secretion levels is a consequence of heterogeneous expression, being dependent on the proportion of bacteria in a population that are actively engaged in protein secretion. This was demonstrated by indirect immunofluorescence and eGFP fusions that examined the expression of locus of enterocyte effacement (LEE)‐encoded factors in individual bacteria. In liquid media, the expression of EspA, tir::egfp, intimin, but not map::egfp were co‐ordinated in a subpopulation of bacteria. In contrast to E. coli O157:H7, expression of tir::egfp in EPEC E2348/69 was equivalent in all bacteria although the same fusion exhibited variable expression when transformed into an E. coli O157:H7 background. An E. coli O157:H7 strain deleted for the LEE demonstrated weak but variable expression of tir::egfp indicating that the elements controlling the heterogeneous expression lie outside the LEE. The research also demonstrated the rapid induction of tir::egfp and map::egfp on contact with bovine epithelial cells. 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.
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2
ISSN:	0950-382X 1365-2958
DOI:	10.1111/j.1365-2958.2004.04277.x