IADR Abstract Archives

Characterization of Streptococcus gordonii fibrils

OBJECTIVE: Viridans Streptoccoci, which include Streptococcus gordonii, are pioneer colonizers of the tooth surface in the human oral cavity, initiating biofilms known as dental plaque. Colonization, survival and pathogenicity of S. gordonii are linked to its ability to elaborate cell surface appendages called fibrils. Although S. gordonii is a well-studied bacterium, little is known about the structure and content of adhesin proteins in the native fibrils. Here we report the extraction, purification and preliminary characterization of S. gordonii fibrils.

METHODS: Fibrils were extracted in urea-extraction buffer by shearing streptococcal cells with glass beads. High molecular mass fibrillar structures were isolated by successive gel filtration chromatography procedures. The preparations were treated with Mutanolysin to remove associated peptidoglycan and the physical appearance of the fibrils was visualized by transmission electron microscopy.

RESULTS: Isolated S. gordonii fibrils appeared to be stable when incubated at 100°C under denaturing conditions in the presence of sodium dodecyl sulfate with mercaptoethanol or dithiothreitol. Using calibrated size exclusion chromatography, we estimated that fibrils formed two fractions, large molecular mass fibrils > 40 x 106 Da and a smaller mass fraction of 20 to 40 x 106 Da. Fibrillar structures appeared to be of two dimensions: long fibrils up to 6 µm in length with a diameter of 70 nm and short fibrils with up to 1 µm long and 40 nm in diameter.

CONCLUSION: S. gordonii fibrils have been partially characterized. From a single strain, the fibrils appear to be of two sizes. These large and small electron-dense fibrils are likely to contain an array of large cell wall anchored proteins. The molecular structure of the fibrils is currently being characterized using mass spectrometry. This project was supported by NIH/NIDCR R01DE08590.


AADR/CADR Annual Meeting
2010 AADR/CADR Annual Meeting (Washington, D.C.)
Washington, D.C.
2010
1426
Microbiology / Immunology and Infection Control
  • Sonan, Kouadio  ( University of Minnesota, Minneapolis, MN, USA )
  • Zhang, Yongshu  ( University of Minnesota, Minneapolis, MN, USA )
  • Ross, Karen  ( University of Minnesota, Minneapolis, MN, USA )
  • Herzberg, Mark  ( University of Minnesota, Minneapolis, MN, USA )
    • Poster Session
    Streptococci
    03/06/2010