title: Multiple mechanisms for the activation of human platelet aggregation by Staphylococcus aureus: roles for the clumping factors ClfA and ClfB, the serine-aspartate repeat protein SdrE and protein A.
abstract: The ability of Staphylococcus aureus cells to induce platelet aggregation has long been recognized. However, despite several attempts to identify the mechanisms involved in this interaction, the nature of the bacterial receptors required remains poorly understood. Using genetic manipulation, this study for the first time provides clear evidence that several S. aureus surface proteins participate in the inter-action with platelets. Mutants of S. aureus strain Newman lacking one or more surface proteins were tested for their ability to stimulate platelet aggregation. This approach was complemented by the expression of a number of candidate proteins in the non-aggregating Gram-positive bacterium Lacto-coccus lactis. S. aureus-induced aggregation was monophasic and was dependent on the platelet receptor GPIIb/IIIa. The fibrinogen-binding proteins, clumping factors A and B and the serine-aspartate repeat protein SdrE could each induce aggregation when expressed in L. lactis. Although protein A expressed in L. lactis was not capable of inducing aggregation independently, it enhanced the aggregation response when expressed on the surface of S. aureus. Thus, S. aureus has multiple mechanisms for stimulating platelet aggregation. Such functional redundancy suggests that this phenomenon may be important in the pathogenesis of invasive diseases such as infective endocarditis.
authors: Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College, Dublin 2, Ireland.
authors: Louise
authors: L
authors: O'Brien
authors: Steven W
authors: SW
authors: Kerrigan
authors: Gideon
authors: G
authors: Kaw
authors: Michael
authors: M
authors: Hogan
authors: José
authors: J
authors: Penadés
authors: David
authors: D
authors: Litt
authors: Desmond J
authors: DJ
authors: Fitzgerald
authors: Timothy J
authors: TJ
authors: Foster
authors: Dermot
authors: D
authors: Cox
mesh_terms: D018829:Adhesins, Bacterial / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D006801:Humans; D013294:Lactococcus lactis / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D010973:Platelet Adhesiveness / Q000187:drug effects; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D011485:Protein Binding; D011994:Recombinant Proteins / Q000378:metabolism; D013205:Staphylococcal Protein A / Q000235:genetics / Q000378:metabolism; D013211:Staphylococcus aureus / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity
chemical_list: D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; D008565:Membrane Proteins; D010975:Platelet Aggregation Inhibitors; D011994:Recombinant Proteins; C118507:SdrE protein, Staphylococcus aureus; D013205:Staphylococcal Protein A; C434058:clfB protein, Staphylococcus aureus