ABSTRACT
In pathogenic Escherichia coli, adhesins have been identified that are not associated with the expression of fimbriae, but — as it seems — are presented on the outer membrane of the bacterial cell as single proteins. Some of these proteins also have the potential to form larger multi-unit aggregates. These proteins have been termed "afimbrial" or "nonfimbrial" (NFA) adhesins. Nonfimbrial adhesins have been isolated from uropathogenic Escherichia coli strains. All NFAs characterized thus far recognize carbohydrate moieties associated with glycophorin A. While NFA-1, 2, 4, 5, and 6 do not seem to distinguish between different glycophorin A types, NFA-3 has a preference for ANN. Characterization of the M hemagglutinin by molecular cloning and biochemical analysis after purification identified the adhesin as a 21-kDa protein, which by electron microscopic studies seemed to form “ring-shaped” aggregates of high molecular mass.
