Type 1 pili-mediated adherence of Escherichia coli strain LF82 isolated from Crohn's disease is involved in bacterial invasion of intestinal epithelial cells.
We previously characterized the invasive ability of Escherichia coli strain LF82, isolated from an ileal biopsy of a patient with Crohn's disease. In the present study, we performed TnphoA insertion mutagenesis to identify genes involved in LF82 invasion of intestinal epithelial cells. Most of the non-invasive mutants had an insertion mutation within the type 1 pili-encoding operon. Two non-invasive fim mutants, which harboured an insertion within the fimI and fimF genes, still adhered but had lost the ability to induce host cell membrane elongations at the sites of contact with the epithelial cells. Transcomplementation experiments with a fim operon cloned from E. coli K-12 restored both invasive ability and the ability to induce host cell membrane elongations. Expression of the cloned LF82 or K-12 fim operon into the non-invasive laboratory strain JM109 did not confer invasive properties. Thus, these findings showed that: (i) type 1 pili-mediated adherence is involved in LF82-induced perturbation of host cell signalling responsible for membrane elongations; (ii) native shafts are required for type 1 pilus-mediated induction of membrane elongations; (iii) this active phenomenon is a key step in the establishment of the invasive process; and (iv) type 1 pili alone are not sufficient to trigger bacterial internalization.
Pathogénie Bactérienne Intestinale, Laboratoire de Bactériologie, Faculté de Pharmacie, Université d'Auvergne, 28, place Henri Dunant, 63001 Clermont-Ferrand, France.
J
J
Boudeau
N
N
Barnich
A
A
Darfeuille-Michaud
D000595:Amino Acid Sequence; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D003424:Crohn Disease / Q000382:microbiology*; D004251:DNA Transposable Elements / Q000235:genetics; D004847:Epithelial Cells / Q000382:microbiology; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000382:microbiology; D010861:Fimbriae, Bacterial / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007421:Intestine, Small / Q000166:cytology / Q000382:microbiology*; D008969:Molecular Sequence Data; D005810:Multigene Family; D016254:Mutagenesis, Insertional
D001426:Bacterial Proteins; D004251:DNA Transposable Elements