Structural basis for sialoglycan binding by the streptococcus sanguinis SrpA adhesin

Barbara A. Bensing, Lioudmila V. Loukachevitch, Kathryn M. Mcculloch, Hai Yu, Kendra R. Vann, Zdzislaw Wawrzak, Spencer Anderson, Xi Chen, Paul M. Sullam, T. M. Iverson*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

33 Scopus citations


Streptococcus sanguinis is a leading cause of infective endocarditis, a life-threatening infection of the cardiovascular system. An important interaction in the pathogenesis of infective endocarditis is attachment of the organisms to host platelets. S. sanguinis expresses a serine-rich repeat adhesin, SrpA, similar in sequence to platelet-binding adhesins associated with increased virulence in this disease. In this study, we determined the first crystal structure of the putative binding region of SrpA (SrpABR) both unliganded and in complex with a synthetic disaccharide ligand at 1.8 and 2.0 Å resolution, respectively.We identified a conserved Thr-Arg motif that orients the sialic acid moiety and is required for binding to platelet monolayers. Furthermore, we propose that sequence insertions in closely related family members contribute to the modulation of structural and functional properties, including the quaternary structure, the tertiary structure, and the ligand-binding site.

Original languageEnglish (US)
Pages (from-to)7230-7240
Number of pages11
JournalJournal of Biological Chemistry
Issue number14
StatePublished - Apr 1 2016

ASJC Scopus subject areas

  • Molecular Biology
  • Biochemistry
  • Cell Biology


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