Implication of an Outer Surface Lipoprotein in Adhesion of Bifidobacterium bifidum to Caco-2 Cells

• Published in: Applied and Environmental Microbiology Vol. 74; no. 15; pp. 4695 - 4702
• Main Authors: Guglielmetti, Simone, Tamagnini, Isabella, Mora, Diego, Minuzzo, Mario, Scarafoni, Alessio, Arioli, Stefania, Hellman, Jukka, Karp, Matti, Parini, Carlo
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Washington, DC American Society for Microbiology 01.08.2008; American Society for Microbiology (ASM)
• Subjects: Bacteria; Bacterial Adhesion - physiology; Bacterial Proteins - isolation & purification; Bacterial Proteins - physiology; Bacteriology; Bifidobacterium - physiology; Bifidobacterium bifidum; Biochemistry; Biological and medical sciences; Caco-2 Cells - microbiology; Cell Wall - physiology; Cells; Colon - microbiology; Feces - microbiology; Fundamental and applied biological sciences. Psychology; Humans; Lipoproteins - physiology; Meeting Presentations; Microbiology; Molecular Sequence Data; Peptides; Proteins; Actinomycetales; Lactic acid bacteria; Actinomycetaceae; Bacteria; Actinomycetes; Lipoprotein; Adhesion; Bifidobacterium bifidum
• ISSN: 0099-2240; 1098-5336; 1098-6596
• DOI: 10.1128/AEM.00124-08

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.