Alternate thermoregulation and functional binding of Escherichia coli type 1 fimbriae in environmental and animal isolates.
Type 1 fimbriae (T1F) are well characterised cell surface organelles expressed by Escherichia coli and required for adherence to mannosylated host tissue. They satisfy molecular Koch's postulates as a virulence determinant and a host-adapted role has been reinforced by reports that T1F expression is repressed at submammalian temperatures. Analysis of a group of 136 environmental and animal E. coli isolates that express T1F at 37°C showed that 28% are also capable of expression at 20°C, in a phase variable manner. The heterogeneous proportions varied widely, and although growth temperature impacted the total proportion expressing T1F, there was no direct correlation between growth at 37°C and 20°C, indicative of differences in thermoregulation of the genetic switch (fimS) that controls phase variation. Specificities of the adhesin (FimH) also varied between the isolates: most bound to α-(1-3) mannan and yeast extracts as expected, but some recognised β-(1-4)-mannans and N-linked glycoproteins from plants, and T1F from two of the isolates mediated binding to plant roots. The results expand our view of a well-described adherence factor to show alternative expression profiles and adhesin specificities, which in turn may confer an advantage for certain isolates in alternative hosts and habitats.
The James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK.
Jacqueline
J
Marshall
The James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK.
Yannick
Y
Rossez
Roslin Institute and Royal (Dick) School of Veterinary Studies, Edinburgh EH25 9RG, UK.
Geoffrey
G
Mainda
Roslin Institute and Royal (Dick) School of Veterinary Studies, Edinburgh EH25 9RG, UK.
David L
DL
Gally
Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.
Tim J
TJ
Daniell
The James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK nicola.holden@hutton.ac.uk.
Nicola J
NJ
Holden
D018830:Adhesins, Escherichia coli / Q000235:genetics / Q000378:metabolism*; D001422:Bacterial Adhesion / Q000502:physiology*; D002457:Cell Extracts / Q000737:chemistry; D004926:Escherichia coli / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D036781:Fimbriae Proteins / Q000378:metabolism; D010861:Fimbriae, Bacterial / Q000378:metabolism*; D006023:Glycoproteins / Q000378:metabolism; D008351:Mannans / Q000378:metabolism; D008358:Mannose / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism / Q000382:microbiology*; D011485:Protein Binding; D013696:Temperature
D018830:Adhesins, Escherichia coli; D002457:Cell Extracts; D006023:Glycoproteins; D008351:Mannans; C058769:fimH protein, E coli; D036781:Fimbriae Proteins; D008358:Mannose
T-RLFP; adhesin; animals; mannosides; pili; plants