Implication of an outer surface lipoprotein in adhesion of Bifidobacterium bifidum to Caco-2 cells.
We found that the human intestinal isolate Bifidobacterium bifidum MIMBb75 strongly adhered to Caco-2 cells. Proteinase K and lithium chloride treatments showed that proteins play a key role in MIMBb75 adhesion to Caco-2 cells. By studying the cell wall-associated proteins, we identified a surface protein, which we labeled BopA. We purified the protein chromatographically and found that it functioned as an adhesion promoter on Caco-2 cells. In silico analysis of the gene coding for this protein and globomycin experiments showed that BopA is a cysteine-anchored lipoprotein expressed as a precursor polypeptide. A database search indicated that BopA appears to function biologically as an oligopeptide/tripeptide-solute-binding protein in the ABC transport system. We discovered a protein corresponding to BopA and its gene in eight other highly adherent B. bifidum strains. Finally, we found that B. bifidum MIMBb75 and BopA affected the production of interleukin-8 in Caco-2 epithelial cells. BopA is the first protein described to date to be directly involved in the adhesion of bifidobacteria to Caco-2 cells and to show immunomodulatory activity.
Department of Food Science and Microbiology, University of Milan, Via Celoria 2, 20133 Milan, Italy. simone.guglielmetti@unimi.it
Simone
S
Guglielmetti
Isabella
I
Tamagnini
Diego
D
Mora
Mario
M
Minuzzo
Alessio
A
Scarafoni
Stefania
S
Arioli
Jukka
J
Hellman
Matti
M
Karp
Carlo
C
Parini
D001422:Bacterial Adhesion / Q000502:physiology*; D001426:Bacterial Proteins / Q000302:isolation & purification / Q000502:physiology*; D001644:Bifidobacterium / Q000502:physiology*; D018938:Caco-2 Cells / Q000382:microbiology; D002473:Cell Wall / Q000502:physiology; D003106:Colon / Q000382:microbiology; D005243:Feces / Q000382:microbiology; D006801:Humans; D008074:Lipoproteins / Q000502:physiology*; D008969:Molecular Sequence Data
D001426:Bacterial Proteins; D008074:Lipoproteins