A double, long polar fimbria mutant of Escherichia coli O157:H7 expresses Curli and exhibits reduced in vivo colonization.
Escherichia coli O157:H7 causes food and waterborne enteric infections that can result in hemorrhagic colitis and life-threatening hemolytic uremic syndrome. Intimate adherence of the bacteria to intestinal epithelial cells is mediated by intimin, but E. coli O157:H7 also possess several other putative adhesins, including curli and two operons that encode long polar fimbriae (Lpf). To assess the importance of Lpf for intestinal colonization, we performed competition experiments between E. coli O157:H7 and an isogenic ΔlpfA1 ΔlpfA2 double mutant in the infant rabbit model. The mutant was outcompeted in the ileum, cecum, and midcolon, suggesting that Lpf contributes to intestinal colonization. In contrast, the ΔlpfA1 ΔlpfA2 mutant showed increased adherence to colonic epithelial cells in vitro. Transmission electron microscopy revealed curli-like structures on the surface of the ΔlpfA1 ΔlpfA2 mutant, and the presence of curli was confirmed by Congo red binding, immunogold-labeling electron microscopy, immunoblotting, and quantitative real-time reverse transcription-PCR (qRT-PCR) measuring csgA expression. However, deletion of csgA, which encodes the major curli subunit, does not appear to affect intestinal colonization. In addition to suggesting that Lpf can contribute to EHEC intestinal colonization, our observations indicate that the regulatory pathways governing the expression of Lpf and curli are interdependent.
Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, USA.
Sonja J
SJ
Lloyd
Jennifer M
JM
Ritchie
Maricarmen
M
Rojas-Lopez
Carla A
CA
Blumentritt
Vsevolod L
VL
Popov
Jennifer L
JL
Greenwich
Matthew K
MK
Waldor
Alfredo G
AG
Torres
D018829:Adhesins, Bacterial / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D000818:Animals; D000831:Animals, Newborn; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002432:Cecum / Q000382:microbiology; D002460:Cell Line; D022081:Cell Surface Extensions / Q000648:ultrastructure; D003106:Colon / Q000382:microbiology; D004847:Epithelial Cells / Q000382:microbiology; D019453:Escherichia coli O157 / Q000235:genetics / Q000472:pathogenicity* / Q000648:ultrastructure; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D036781:Fimbriae Proteins / Q000235:genetics / Q000378:metabolism*; D010861:Fimbriae, Bacterial / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D017353:Gene Deletion; D020869:Gene Expression Profiling; D006801:Humans; D007082:Ileum / Q000382:microbiology; D011817:Rabbits
D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C571199:LpfA1 protein, E coli; C571200:LpfA2 protein, E coli; D036781:Fimbriae Proteins; C077481:Crl protein, Bacteria