Purification of a bone sialoprotein‐binding protein from Staphylococcus aureus

Abstract

Bone sialoprotein (BSP) is selectively bound by Staphylococcus aureus cells isolated from patients suffering from infections of bone and joint tissues [Rydén C., Maxe, I., Franzén, A., Ljungh, Å., Heinegård, D. & Rubin, K. (1987) Lancet II, 515]. We now report on the purification of a cell‐wall protein from Staphylococcus aureus, strain O24, that possesses affinity for bone sialoprotein. Staphylococcal cell‐wall components with capacity to inhibit binding of 125I‐labeled BSP to staphylococcal cells were solubilized with LiCl (1.0 M, pH 5.0). Preparative SDS/PAGE and protein‐overlay experiments revealed that inhibitory activity present in LiCl extracts resided in a fraction of polypeptides with Mr 75000–110000. Staphylococcal proteins solubilized with LiCl were chromatographed on a Mono‐Q anion‐exchange column. Inhibitory activity was eluted at 0.6–0.8 M NaCl and could be further purified by affinity chromatography on BSP‐Sepharose. Elution of the affinity matrix with 0.1 M glycine, pH 3.0, specifically eluted inhibitory activity. Analysis by SDS/PAGE revealed a single Mr 97000 polypeptide in the eluate. The purified Mr 97000 protein bound BSP in protein‐overlay experiments. LiCl extracts from S. aureus, strain E514 or Staphylococcus epidermidis, strain 7686, both lacking the capacity to bind BSP did not contain the Mr 97000 protein. Our data demonstrate the presence of a S. aureus, cell‐surface BSP‐binding protein. This protein could be involved in bacterial tropism in osteomyelitis.

Staphylococcus aureusFibronectin Binding Proteins Are Essential for Internalization by Osteoblasts but Do Not Account for Differences in Intracellular Levels of Bacteria

“…However, only about 38 to 56% of S. aureus isolates associated with bone infection express Cna (30,32). On the other hand, the bone sialoprotein binding protein of S. aureus has been shown to be preferentially expressed by isolates from patients with osteomyelitis and/or septic arthritis (28,29,33). Thus, it is not clear which, if any, of these staphylococcal proteins are responsible for targeting S. aureus to bone.…”

Staphylococcus aureus adhesion to bone matrix and bone-associated biomaterials

“…The S. aureus bone sialoprotein adhesin is therefore distinct from any of the previously characterized S. aureus cell-surface proteins. A 97-kDa protein has now been puri¢ed from S. aureus strain O24 that possesses an a¤nity for bone sialoprotein [24]. This protein was not present in a S. aureus strain that lacked bone sialoprotein-binding ability.…”

Acute Septic Arthritis

“…aureus has a variety of receptors, termed microbial surface components recognizing adhesive matrix molecules (MSCRAMMs), for host proteins that mediate adherence to the joint extracellular matrix or implanted medical devices (68,142,189). Some of the host matrix proteins include fibronectin and laminin (adherence proteins), elastin (imparts elastic properties), collagen (structural support), and hyaluronic acid (a glycosaminoglycan that is rich in the joints and the matrix and provides cushioning through hydration of its polysaccharides).…”