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Identification of a Novel Streptococcal Adhesin P (SadP) Protein Recognizing Galactosyl-alpha 1-4-galactose-containing Glycoconjugates CONVERGENT EVOLUTION OF BACTERIAL PATHOGENS TO BINDING OF THE SAME HOST RECEPTOR

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Author

  • Annika Kouki
  • Sauli Haataja
  • Vuokko Loimaranta
  • Arto T. Pulliainen
  • Ulf Nilsson
  • Jukka Finne

Summary, in English

Bacterial adhesion is often a prerequisite for infection, and host cell surface carbohydrates play a major role as adhesion receptors. Streptococci are a leading cause of infectious diseases. However, only few carbohydrate-specific streptococcal adhesins are known. Streptococcus suis is an important pig pathogen and a zoonotic agent causing meningitis in pigs and humans. In this study, we have identified an adhesin that mediates the binding of S. suis to galactosyl-alpha 1-4-galactose (Gal alpha 1-4Gal)-containing host receptors. A functionally unknown S. suis cell wall protein (SSU0253), designated here as SadP (streptococcal adhesin P), was identified using a Gal alpha 1-4Gal-containing affinity matrix and LC-ESI mass spectrometry. Although the function of the protein was not previously known, it was recently identified as an immunogenic cell wall protein in a proteomic study. Insertional inactivation of the sadP gene abolished S. suis Gal alpha 1-4Gal-dependent binding. The adhesin gene sadP was cloned and expressed in Escherichia coli. Characterization of its binding specificity showed that SadP recognizes Gal alpha 1-4Gal-oligosaccharides and binds its natural glycolipid receptor, GbO(3) (CD77). The N terminus of SadP was shown to contain a Gal alpha 1-Gal-binding site and not to have apparent sequence similarity to other bacterial adhesins, including the E. coli P fimbrial adhesins, or to E. coli verotoxin or Pseudomonas aeruginosa lectin I also recognizing the same Gal alpha 1-4Gal disaccharide. The SadP and E. coli P adhesins represent a unique example of convergent evolution toward binding to the same host receptor structure.

Publishing year

2011

Language

English

Pages

38854-38864

Publication/Series

Journal of Biological Chemistry

Volume

286

Issue

45

Document type

Journal article

Publisher

American Society for Biochemistry and Molecular Biology

Topic

  • Organic Chemistry

Status

Published

ISBN/ISSN/Other

  • ISSN: 1083-351X