Efficient utilization of complex N-linked glycans is a selective advantage for Bacteroides fragilis in extraintestinal infections

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 111; no. 35; pp. 12901 - 12906
• Main Authors: Cao, Yanlu, Rocha, Edson R., Smith, C. Jeffrey
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 02-09-2014; National Acad Sciences
• Subjects: Abscess - metabolism; Abscess - microbiology; Anaerobiosis; Animals; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacteroides; Bacteroides fragilis; Bacteroides fragilis - genetics; Bacteroides fragilis - growth & development; Bacteroides fragilis - metabolism; Bacteroides Infections - metabolism; Bacteroides Infections - microbiology; Biological Sciences; Body Fluids - metabolism; Body Fluids - microbiology; Carbon - metabolism; Culture diffusion chambers; Culture Media - metabolism; Diffusion Chambers, Culture - microbiology; Digestive system; Disease Models, Animal; Glucose - metabolism; Glycoproteins; Glycoproteins - blood; Glycoproteins - metabolism; Glycosylation; Gram-negative bacteria; Humans; Infections; Microbiota; Operons; Phylogeny; Polysaccharides; Polysaccharides - metabolism; Proteins; Rats; RNA; Swine; Transferrin - metabolism; Transferrins
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1407344111

Bacteroides fragilis is the most common anaerobe isolated from clinical infections, and in this report we demonstrate a characteristic of the species that is critical to their success as an opportunistic pathogen. Among the Bacteroides spp. in the gut, B. fragilis has the unique ability of efficiently harvesting complex N-linked glycans from the glycoproteins common to serum and serous fluid. This activity is mediated by an outer membrane protein complex designated as Don. Using the abundant serum glycoprotein transferrin as a model, it has been shown that B. fragilis alone can rapidly and efficiently deglycosylate this protein in vitro and that transferrin glycans can provide the sole source of carbon and energy for growth in defined media. We then showed that transferrin deglycosylation occurs in vivo when B. fragilis is propagated in the rat tissue cage model of extraintestinal growth, and that this ability provides a competitive advantage in vivo over strains lacking the don locus.