by Yan Su
The bacterium Streptococcus sanguinis is one of the major causes of bacterial infective endocarditis, a life-threatening infection of the cardiovascular system.
S. sanguinis binding to platelets is one of the first required steps for infection. To understand the interaction between S. sanguinis and platelets, Tina Iverson, Ph.D., and colleagues studied the serine-rich adhesive protein, SrpA. SrpA is expressed by S. sanguinis and binds human platelets with high affinity.
The investigators obtained X-ray crystal structures of the binding region of SrpA alone or combined with a synthetic disaccharide ligand, and they identified a ligand binding Thr-Arg motif. In addition, they used site-directed mutagenesis to alter key residues and validate the residues important for platelet binding.
The findings, highlighted as a “Paper of the Week” in the April 1 issue of The Journal of Biological Chemistry, provide a structural and molecular basis for the design of potentially novel anti-Streptococcus sanguinis therapeutics.
This research was supported by the Department of Veterans Affairs, the National Institutes of Health (grants AI041513, AI106987) and the American Heart Association.
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