Functional heterogeneity of type 1 fimbriae of Escherichia coli.
Escherichia coli and other members of the family Enterobacteriaceae express surface fibrillar structures, fimbriae, that promote bacterial adhesion to host receptors. Type 1 fimbriae possess a lectinlike component, FimH, that is commonly thought to cause binding to mannose-containing oligosaccharides of host receptors. Since adhesion of type 1 fimbriated organisms are inhibited by mannose, the reactions are described as mannose sensitive (MS). We have studied the adhesion of the type 1 fimbriated CSH-50 strain of E. coli (which expresses only type 1 fimbriae) to fibronectin (FN). E. coli CSH-50 does not bind detectable amounts of soluble FN but adheres well to immobilized plasma or cellular FN. This adhesion was inhibited by mannose-containing saccharides. By using purified domains of FN, it was found that E. coli CSH-50 adheres primarily to the amino-terminal and gelatin-binding domains, only one of which is glycosylated, in an MS fashion. Binding of the mannose-specific lectin concanavalin A to FN and ovalbumin was eliminated or reduced, respectively, by incubation with periodate or endoglycosidase. Adhesion of E. coli CSH-50 to ovalbumin was reduced by these treatments, but adhesion to FN was unaffected. E. coli CSH-50 also adheres to a synthetic peptide copying a portion of the amino-terminal FN domain (FNsp1) in an MS fashion. Purified CSH-50 fimbriae bound to immobilized FN and FNsp1 in an MS fashion and inhibited adhesion of intact organisms. However, fimbriae purified from HB101 (pPKL4), a recombinant strain harboring the entire type 1 fim gene locus and expressing functional type 1 fimbriae, neither bound to FN or FNsp1 nor inhibited E. coli adhesion to immobilized FN or FNsp1. These novel findings suggest that there are two forms of type 1 MS fimbriae. One form exhibits only the well-known MS lectinlike activity that requires a substratum of mannose-containing glycoproteins. The other form exhibits not only the MS lectinlike activity but also binds to nonglycosylated regions of proteins in an MS manner.
Sokurenko
E V
EV
Department of Anatomy and Neurobiology, University of Tennessee, Memphis 38104.
Courtney
H S
HS
Abraham
S N
SN
Klemm
P
P
Hasty
D L
DL
D001422:Bacterial Adhesion; D001665:Binding Sites; D004926:Escherichia coli / Q000472:pathogenicity*; D005353:Fibronectins / Q000378:metabolism; D010861:Fimbriae, Bacterial / Q000378:metabolism*; D006388:Hemagglutinins / Q000378:metabolism; D006801:Humans; D010084:Oxidation-Reduction; D010446:Peptide Fragments / Q000378:metabolism; D010504:Periodic Acid / Q000737:chemistry; D013211:Staphylococcus aureus / Q000472:pathogenicity
D005353:Fibronectins; D006388:Hemagglutinins; D010446:Peptide Fragments; D010504:Periodic Acid