The oxidoreductase DsbA plays a key role in the ability of the Crohn's disease-associated adherent-invasive Escherichia coli strain LF82 to resist macrophage killing.
Adherent-invasive Escherichia coli (AIEC) isolated from Crohn's disease patients is able to adhere to and invade intestinal epithelial cells and to replicate in mature phagolysosomes within macrophages. Here, we show that the dsbA gene, encoding a periplasmic oxidoreductase, was required for AIEC strain LF82 to adhere to intestinal epithelial cells and to survive within macrophages. The LF82-DeltadsbA mutant did not express flagella and, probably as a consequence of this, did not express type 1 pili. The role of DsbA in adhesion is restricted to the loss of flagella and type 1 pili, as forced contact between bacteria and cells and induced expression of type 1 pili restored the wild-type phenotype. In contrast, the dsbA gene is essential for AIEC LF82 bacteria to survive within macrophages, irrespective of the loss of flagella and type 1 pilus expression, and the survival ability of LF82-DeltadsbA was as low as that of the nonpathogenic E. coli K-12, which was efficiently killed by macrophages. We also provide evidence that the dsbA gene is needed for LF82 bacteria to grow and survive in an acidic and nutrient-poor medium that partly mimics the harsh environment of the phagocytic vacuole. In addition, under such stress conditions dsbA transcription is highly up-regulated. Finally, the CpxRA signaling pathway does not play a role in regulation of dsbA expression in AIEC LF82 bacteria under conditions similar to those of mature phagolysosomes.
Bringer
Marie-Agnès
MA
Pathogénie Bactérienne Intestinale, Université Clermont I, USC INRA 2018, F-63000 Clermont-Fd, France.
Rolhion
Nathalie
N
Glasser
Anne-Lise
AL
Darfeuille-Michaud
Arlette
A
D000818:Animals; D001422:Bacterial Adhesion / Q000235:genetics / Q000502:physiology; D002460:Cell Line; D003424:Crohn Disease / Q000382:microbiology*; D004847:Epithelial Cells / Q000382:microbiology; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development / Q000648:ultrastructure; D004927:Escherichia coli Infections / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D010861:Fimbriae, Bacterial / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D005816:Genetic Complementation Test; D006863:Hydrogen-Ion Concentration; D015151:Immunoblotting; D007422:Intestines / Q000166:cytology / Q000382:microbiology; D008264:Macrophages / Q000166:cytology / Q000382:microbiology*; D051379:Mice; D046529:Microscopy, Electron, Transmission; D009154:Mutation; D010084:Oxidation-Reduction; D019704:Protein Disulfide-Isomerases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors
D029968:Escherichia coli Proteins; D019704:Protein Disulfide-Isomerases