title: Evidence for specificity in type 4 pilus biogenesis by enteropathogenic Escherichia coli.
abstract: Type 4 fimbriae (pili) are surface appendages that are expressed by many species of Gram-negative bacteria. Previous studies have demonstrated that Pseudomonas aeruginosa can express and assemble pilin subunits from several unrelated species, indicating a common mechanism for biogenesis of type 4 pili whereby structural subunits from one system may be interchanged with those of another. In this study, an isogenic mutant of enteropathogenic Escherichia coli (EPEC) was constructed containing the entire tcpA gene from Vibrio cholerae 0395, which encodes the major structural subunit of the toxin-coregulated pilus (TCP), in place of bfpA, which encodes the major structural subunit of the bundle-forming pilus (BFP). Surprisingly, expression of type 4 pilin structures and the associated phenotype of bacterial autoaggregation in culture media were not observed for cells of the EPEC strain containing tcpA nor for those containing an additional mutation in bfpF, which otherwise is associated with a hyperfimbriate phenotype. In addition, cells of a bfpA mutant EPEC strain containing plasmids designed to express either of two different chimeric type 4 pilin subunits containing segments of BfpA and TcpA also failed to form bacterial aggregates and express type 4 pilin structures. Collectively, these results indicate that the type 4 pilin assembly system of EPEC exhibits specificity with regard to pilin subunit recognition and assembly.
authors.affiliation: Division of Infectious Diseases, Department of Medicine, University of Maryland School of Medicine, 10 South Pine Street, Room 900, Baltimore, MD 21201, USA1.
authors.forename: Barry P
authors.initials: BP
authors.lastname: McNamara
authors.affiliation: Division of Infectious Diseases, Department of Medicine, University of Maryland School of Medicine, 10 South Pine Street, Room 900, Baltimore, MD 21201, USA1.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Donnenberg
mesh_terms: D001422:Bacterial Adhesion; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D029968:Escherichia coli Proteins; D036781:Fimbriae Proteins; D010861:Fimbriae, Bacterial / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D015151:Immunoblotting; D008565:Membrane Proteins / Q000378:metabolism; D008854:Microscopy, Electron; D010957:Plasmids / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D011995:Recombination, Genetic; D014407:Tumor Cells, Cultured; D014734:Vibrio cholerae / Q000235:genetics
chemical_list: D001425:Bacterial Outer Membrane Proteins; C104901:BfpA protein, E coli; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; C085807:TcpA protein, Vibrio cholerae; D036781:Fimbriae Proteins