Staphylococcus aureus SasA is responsible for binding to the salivary agglutinin gp340, derived from human saliva

Infect Immun. 2013 Jun;81(6):1870-9. doi: 10.1128/IAI.00011-13. Epub 2013 Feb 25.


Staphylococcus aureus is a major human pathogen that can colonize the nasal cavity, skin, intestine, and oral cavity as a commensal bacterium. gp340, also known as DMBT1 (deleted in malignant brain tumors 1), is associated with epithelial differentiation and innate immunity. In the oral cavity, gp340 induces salivary aggregation with several oral bacteria and promotes bacterial adhesion to tissues such as the teeth and mucosa. S. aureus is often isolated from the oral cavity, but the mechanism underlying its persistence in the oral cavity remains unclear. In this study, we investigated the interaction between S. aureus and gp340 and found that S. aureus interacts with saliva- and gp340-coated resin. We then identified the S. aureus factor(s) responsible for binding to gp340. The cell surface protein SasA, which is rich in basic amino acids (BR domain) at the N terminus, was responsible for binding to gp340. Inactivation of the sasA gene resulted in a significant decrease in S. aureus binding to gp340-coated resin. Also, recombinant SasA protein (rSasA) showed binding affinity to gp340, which was inhibited by the addition of N-acetylneuraminic acid. Surface plasmon resonance analysis showed that rSasA significantly bound to the NeuAcα(2-3)Galβ(1-4)GlcNAc structure. These results indicate that SasA is responsible for binding to gp340 via the N-acetylneuraminic acid moiety.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Calcium-Binding Proteins
  • DNA-Binding Proteins
  • Gene Expression Regulation, Bacterial / physiology
  • Humans
  • Male
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism
  • Middle Aged
  • Mutation
  • N-Acetylneuraminic Acid / chemistry
  • Phosphotransferases / chemistry
  • Phosphotransferases / metabolism*
  • Protein Binding
  • Receptors, Cell Surface / chemistry
  • Receptors, Cell Surface / isolation & purification
  • Receptors, Cell Surface / metabolism*
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Saliva / chemistry
  • Staphylococcus aureus / enzymology*
  • Staphylococcus aureus / genetics
  • Staphylococcus aureus / metabolism
  • Tumor Suppressor Proteins


  • Bacterial Proteins
  • Calcium-Binding Proteins
  • DMBT1 protein, human
  • DNA-Binding Proteins
  • Membrane Proteins
  • Receptors, Cell Surface
  • Recombinant Proteins
  • Tumor Suppressor Proteins
  • Phosphotransferases
  • N-Acetylneuraminic Acid