title: Gene clusters for S fimbrial adhesin (sfa) and F1C fimbriae (foc) of Escherichia coli: comparative aspects of structure and function.
abstract: Fimbrial adhesins enable bacteria to attach to eucaryotic cells. The genetic determinants for S fimbrial adhesins (sfa) and for F1C ("pseudotype I") fimbriae (foc) were compared. Sfa and F1C represent functionally distinct adhesins in their receptor specificities. Nevertheless, a high degree of homology between both determinants was found on the basis of DNA-DNA hybridizations. Characteristic differences in the restriction maps of the corresponding gene clusters, however, were visible in regions coding for the fimbrial subunits and for the S-specific adhesin. While a plasmid carrying the genetic determinant for F1C fimbriae was able to complement transposon-induced sfa mutants, a plasmid carrying the genetic determinant for a third adhesin type, termed P fimbriae, was unable to do so. Proximal sfa-specific sequences carrying the S fimbrial structural gene were fused to sequences representing the distal part of the foc gene cluster to form a hybrid cluster, and the foc proximal region coding for the structural protein was ligated to sfa distal sequences to form a second hybrid. Both hybrid clones produced intact fimbriae. Anti-F1C monoclonal antibodies (MAbs) only recognized clones which produced F1C fimbriae, and an anti-S adhesin MAb marked clones which expressed the S adhesin. However, one of four other anti-S fimbriae-specific MAbs reacted with both fimbrial structures, S and F1C, indicating a common epitope on both antigens. The results presented here support the view that sfa and foc determinants code for fimbriae that are similar in several aspects, while the P fimbriae are members of a more distantly related group.
mesh_terms: D018830:Adhesins, Escherichia coli; D001422:Bacterial Adhesion; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics*; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure; D010861:Fimbriae, Bacterial / Q000502:physiology*; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D005810:Multigene Family; D009693:Nucleic Acid Hybridization; D010957:Plasmids; D012689:Sequence Homology, Nucleic Acid
chemical_list: D018830:Adhesins, Escherichia coli; D001425:Bacterial Outer Membrane Proteins; D004269:DNA, Bacterial