title: Antigen-43-mediated autoaggregation of Escherichia coli is blocked by fimbriation.
abstract: Antigen 43 (Ag43), the product of the flu gene, is a surface-displayed autotransporter protein of Escherichia coli. Ag43 is responsible for the autoaggregation and flocculation of static liquid cultures of many E. coli strains. The expression of Ag43 has been reported to be phase variable and controlled by the product of the oxyR gene. Type 1 fimbriae are thin adhesive thread-like surface organelles responsible for bacterial receptor recognition and tissue colonization. Like that of Ag43, the expression of type 1 fimbriae is phase variable. Interestingly, previous results have suggested that the expression of type 1 fimbriae and the expression of Ag43 are mutually exclusive. In the present report, we show, by use of well-defined mutants, that fimbriation abolishes Ag43-mediated autoaggregation but does not affect Ag43 expression. Autoaggregation is shown to require an intercellular Ag43-Ag43 interaction, and the physical presence of fimbriae on the cells seems to abrogate this interaction. The Ag43 or OxyR status does not appear to influence fimbria expression, and our results suggest that the expression of Ag43 and the expression of fimbriae are independent processes.
authors.affiliation: Department of Microbiology, Technical University of Denmark, DK-2800 Lyngby, Denmark.
authors.forename: H
authors.initials: H
authors.lastname: Hasman
authors.forename: T
authors.initials: T
authors.lastname: Chakraborty
authors.forename: P
authors.initials: P
authors.lastname: Klemm
mesh_terms: D018829:Adhesins, Bacterial; D018830:Adhesins, Escherichia coli; D000942:Antigens, Bacterial / Q000235:genetics / Q000378:metabolism; D001422:Bacterial Adhesion / Q000502:physiology*; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D003001:Cloning, Molecular; D017931:DNA Primers; D004268:DNA-Binding Proteins; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D029968:Escherichia coli Proteins; D010861:Fimbriae, Bacterial / Q000378:metabolism*; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D007700:Kinetics; D008969:Molecular Sequence Data; D009068:Movement; D010641:Phenotype; D010957:Plasmids; D020239:Receptor Cross-Talk; D012097:Repressor Proteins / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics
chemical_list: D018829:Adhesins, Bacterial; D018830:Adhesins, Escherichia coli; D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D017931:DNA Primers; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C118376:antigen 43, E coli; C499299:oxyR protein, E coli