title: Hyperadhesive mutant of type 1-fimbriated Escherichia coli associated with formation of FimH organelles (fimbriosomes).
abstract: The relationships of the genes and gene-products mediating D-mannose-specific attachment of type 1 fimbriae of Escherichia coli to eucaryotic cells were investigated by deletion mutation analysis of recombinant plasmid pSH2, which carries the genetic information for the synthesis and expression of functional type 1 fimbriae. Mutant pUT2004 was derived by a deletion remote from the structural gene encoding the 17-kilodalton (kDa) subunit protein of type 1 fimbriae. Phenotypically, the mutant demonstrated an eightfold-higher mannose-specific hemagglutination titer than the parent strain. On electron microscopy, the mutant strain expressed the same number of fimbriae as the parent strain. However, numerous 10-nm-diameter rounded structures (fimbriosomes) were observed both closely associated with fimbriae and in the culture medium. Fimbriosomes isolated from the medium agglutinated guinea pig erythrocytes in a mannose-sensitive manner. Dissociation of the fimbriosomes yielded a single 29-kDa protein, as demonstrated by sodium dodecyl sulfate gel electrophoresis. Antibodies raised against fimbriosomes reacted with a 29-kDa protein on immunoelectroblots of dissociated type 1 fimbriae and also blocked the adherence of other strains of type 1 fimbriated E. coli to eucaryotic cells. These findings suggest that the enhanced adhesive properties of the mutant pUT2004 strain are associated with overproduction of the 29-kDa FimH in the form of fimbriosomes which contain the determinant of the D-mannose-sensitive adhesion of type 1 fimbriae.
mesh_terms: D001422:Bacterial Adhesion; D004252:DNA Mutational Analysis; D004926:Escherichia coli / Q000235:genetics / Q000472:pathogenicity / Q000648:ultrastructure*; D010861:Fimbriae, Bacterial / Q000648:ultrastructure*; D005786:Gene Expression Regulation; D007158:Immunologic Techniques; D008562:Membrane Glycoproteins / Q000235:genetics*; D008840:Microfilament Proteins; D008854:Microscopy, Electron; D008970:Molecular Weight; D009154:Mutation
chemical_list: D008562:Membrane Glycoproteins; D008840:Microfilament Proteins; C026742:plastin