Molecular Biology of Escherichia coli Type 1 Fimbriae
Most strains of Escherichia coli are able to express type 1 fimbriae. These are thread-like surface organelles consisting of around 1000 subunits of a major structural component, the FimA protein, as well as a few percent minor components. Type 1 fimbriae mediate binding to D-mannose containing structures and thereby enable the bacteria to colonize various host tissues (1, 2). Inhibition of binding of type 1 fimbriated bacteria as well as purified type 1 fimbriae to various cell types has been extensively studied. In all cases it was found that D-mannose itself and most derivatives of this sugar were very potent inhibitors of type 1 fimbriae mediated adhesion, whereas all saccharides not containing D-mannose showed no inhibitory effect. It has been proposed that the biological role of type 1 fimbriae is to provide bacterial adhesion to mucus in the large intestine which is the natural habitat of E. coli. Furthermore, several lines of evidence point to a role of type 1 fimbriae as possible virulence factors in uropathogenic E. coli strains.
KeywordsPhase Switch Integration Host Factor HB101 Cell Export Machinery Fimbrial Adhesins
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