A new immunoglobulin-binding protein, EibG, is responsible for the chain-like adhesion phenotype of locus of enterocyte effacement-negative, shiga toxin-producing Escherichia coli.
Shiga toxin-producing Escherichia coli (STEC) are important enteropathogens causing severe diseases such as hemorrhagic colitis and hemolytic-uremic syndrome in humans. The majority of STEC strains of serogroups O157, O26, or O111 associated with severe cases of these diseases possess a pathogenicity island termed the locus of enterocyte effacement (LEE). LEE, which is responsible for the formation of attaching-and-effacing lesions on intestinal epithelial cells, is important for the full virulence of STEC. Nonetheless, LEE-negative STEC strains have repeatedly been reported to be associated with severe diseases in humans. In this study, we characterized adhesion to cultured epithelial cells of certain LEE-negative STEC isolated from humans with or without bloody diarrhea. Several LEE-negative STEC belonging to serogroup O91 showed an unusual, chain-like adhesion pattern to HEp-2 cells. Using Tn5-based transposon mutagenesis, we identified the gene essential for the chain-like adhesion phenotype of this O91 STEC strain. Sequence analysis of the Tn5-inserted allele identified a novel chromosomal open reading frame (ORF) encoding a polypeptide with a high degree of similarity to the E. coli immunoglobulin-binding (Eib) proteins EibA, -C, -D, -E, and -F. Therefore, the ORF was designated EibG. Laboratory E. coli strain MC4100 transformed with a multicopy plasmid carrying eibG showed chain-like adhesion to HEp-2 cells, and whole-cell lysates of the strain bound to human-derived immunoglobulin G (IgG) Fc and IgA. These results indicate that EibG acts as an IgG Fc- and IgA-binding protein, as well as an adhesin of LEE-negative STEC.
Lu
Yan
Y
Department of Bacteriology, National Institute of Infectious Diseases, Toyama 1-23-1, Shinjuku-ku, Tokyo 162-8640, Japan. siyoda@nih.go.jp.
Iyoda
Sunao
S
Satou
Hiromi
H
Satou
Hitomi
H
Itoh
Kenichiro
K
Saitoh
Takehito
T
Watanabe
Haruo
H
D018830:Adhesins, Escherichia coli / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D001422:Bacterial Adhesion; D002478:Cells, Cultured; D004251:DNA Transposable Elements; D003967:Diarrhea / Q000276:immunology / Q000382:microbiology; D020895:Enterocytes / Q000382:microbiology; D004926:Escherichia coli / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000276:immunology / Q000382:microbiology; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008222:Lymphokines / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D010750:Phosphoproteins / Q000235:genetics; D022621:Shiga Toxin / Q000096:biosynthesis*; D014170:Transformation, Genetic
D018830:Adhesins, Escherichia coli; D004251:DNA Transposable Elements; C514972:EibG protein, E coli; D029968:Escherichia coli Proteins; C457340:LEE protein, E coli; D008222:Lymphokines; D010750:Phosphoproteins; C013059:immunoglobulin-binding factors; D022621:Shiga Toxin