<i>Staphylococcus aureus</i>Fibronectin Binding Protein-A Induces Motile Attachment Sites and Complex Actin Remodeling in Living Endothelial Cells

Abstract

Staphylococcus aureus fibronectin binding protein-A (FnBPA) stimulates alpha5beta1-integrin signaling and actin rearrangements in host cells. This eventually leads to invasion of the staphylococci and their targeting to lysosomes. Using live cell imaging, we found that FnBPA-expressing staphylococci induce formation of fibrillar adhesion-like attachment sites and translocate together with them on the surface of human endothelial cells (velocity approximately 50 microm/h). The translocating bacteria recruited cellular actin and Rab5 in a cyclic and alternating manner, suggesting unsuccessful attempts of phagocytosis by the endothelial cells. Translocation, actin recruitment, and eventual invasion of the staphylococci was regulated by the fibrillar adhesion protein tensin. The staphylococci also regularly produced Neural Wiskott-Aldrich syndrome protein-controlled actin comet tails that further propelled them on the cell surface (velocity up to 1000 microm/h). Thus, S. aureus FnBPA produces attachment sites that promote bacterial movements but subvert actin- and Rab5 reorganization during invasion. This may constitute a novel strategy of S. aureus to postpone invasion until its toxins become effective.