A serine-rich glycoprotein of Streptococcus sanguis mediates adhesion to platelets via GPIb

Christopher Plummer, Hui Wu, Steven W. Kerrigan, Gerardene Meade, Dermot Cox, C. W.Ian Douglas

Research output: Contribution to journalArticlepeer-review

154 Scopus citations


Streptococcus sanguis is the most common oral bacterium causing infective endocarditis and its ability to adhere to platelets, leading to their activation and aggregation, is thought to be an important virulent factor. Previous work has shown that S. sanguis can bind directly to platelet glycoprotein (GP) Ib but the nature of the adhesin was unknown. Here, we have shown that a high molecular weight glycoprotein of S. sanguis mediates adhesion to glycocalacin. The bacterial glycoprotein was purified from cell extracts by chromatography on GPIb- and wheatgerm agglutinin affinity matrices and its interaction with GPIb was shown to be sialic acid-dependent. We designated the glycoprotein serine-rich protein A (SrpA). An insertional inactivation mutant lacking the SrpA of S. sanguis showed significantly reduced binding to glycocalacin, reduced adherence to platelets and a prolonged lag time to platelet aggregation. In addition, under flow conditions, platelets rolled and subsequently adhered on films of wild-type S. sanguis cells at low shear (50/s) but did not bind to films of the SrpA mutant. Platelets did not bind to wild-type bacterial cells at high shear (1500/s). These findings help to understand the mechanisms by which the organism might colonize platelet-fibrin vegetations.

Original languageEnglish (US)
Pages (from-to)101-109
Number of pages9
JournalBritish Journal of Haematology
Issue number1
StatePublished - Apr 2005
Externally publishedYes


  • Glycoprotein Ib
  • Infective endocarditis
  • Platelet adhesion
  • Streptococcus sanguis

ASJC Scopus subject areas

  • Hematology


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