The focus of my laboratory is the pathogenesis of
endovascular infections due to gram positive bacteria. We are currently
examining the mechanisms by which staphylococci and streptococci bind
to human platelets, and how this interaction contributes to the pathogenesis
of infective endocarditis. The binding of bacteria to platelets is
likely to be important for the initial colonization of the endovascular
surface, and for the subsequent formation of macroscopic endocardial
lesions. In addition, platelet-bacterium binding may facilitate the
dissemination of infection to extra-cardiac sites.
Our studies indicate that these organisms can bind to platelets by
a variety of bacterial surface components, and that each species is
likely to express multiple adhesins. For example, Streptococcus
mitis appears to bind platelets in part by two surface proteins
(PblA and PblB) that are encoded by a lysogenic bacteriophage. Platelet
binding by Streptococcus gordonii is mediated partially by
a large surface protein (GspB). Of note, the gene encoding GspB is
part of an operon containing homologs of the Sec system that are essential
for GspB export. We are now in the process of characterizing further
these and other possible adhesins, as well as their binding sites
on the platelet membrane. |
1. Bensing BA, I. Siboo, and Sullam PM. Proteins PblA and PblB of Streptococcus mitis , which promote binding to human platelets, are encoded within a lysogenic bacteriophage. Infect Immun 69:6186-6192 2001.
2. Bensing BA, and Sullam PM. An accessory sec locus of Streptococcus gordonii is required for export of the surface protein GspB and for normal levels of binding to human platelets. Mol Microbiol 44: 1081 -1094, 2002.
3. Bensing BA, Gibson BW, Sullam PM . The Streptococcus gordonii platelet binding protein GspB undergoes glycosylation independently of export. J Bacteriol. 186:638-645, 2004.
4. Bensing BA, Lopez, JA Sullam PM . The Streptococcus gordonii surface proteins GspB and Hsa mediate binding to sialylated carbohydrate epitopes on the platelet membrane glycoprotein Ib a . Infect Immun 72:6528-6537, 2004.
5. Siboo IR, Chambers, HF, Sullam, PM . Role of SraP, a serine-rich surface protein of Staphylococcus aureus , in binding to human platelets. Infect Immun 73:2273-2280, 2005.
6.
Takamatsu D, Bensing BA, Cheng H, Jarvis G, Siboo IR, López JA, Griffiss JM, and Sullam PM . Binding of the Streptococcus gordonii surface glycoprotein GspB and Hsa to specific carbohydrate structures on platelet membrane glycoprotein Ib a . Mol Microbiol 58:380-392, 2005.
7. Takamatsu D, Bensing BA, Prakobphol A, Fisher and Sullam PM . Binding of the Streptococcus gordonii surface glycoproteins GspB and Hsa to human salivary proteins. Infect Immun 74:1933-1940, 2006.
information last updated January 2007 |
Biomedical Sciences (BMS) Graduate Program
