A bone sialoprotein-binding protein from Staphylococcus aureus: a member of the staphylococcal Sdr family

Abstract

Staphylococcus aureus bacteria, isolated from bone and joint infections, specifically interact with bone sialoprotein (BSP), a glycoprotein of bone and dentine extracellular matrix, via a cell-surface protein of M(r) 97000 [Yacoub, Lindahl, Rubin, Wendel, Heinegârd and Rydén, (1994) Eur. J. Biochem. 222, 919-925]. Amino acid sequences of seven trypsin fragments from the 97000-M(r) BSP-binding protein were determined. A gene encoding a protein encompassing all seven peptide sequences was identified from chromosomal DNA isolated from S. aureus strain O24. This gene encodes a protein with 1171 amino acids, called BSP-binding protein (Bbp), which displays similarity to recently described proteins of the Sdr family from S. aureus. SdrC, SdrD and SdrE encode putative cell-surface proteins with no described ligand specificity. Bbp also shows similarity to a fibrinogen-binding protein from S. epidermidis called Fbe. A serine-aspartic acid repeat sequence was found close to the cell-wall-anchoring Leu-Pro-Xaa-Thr-Gly sequence in the C-terminal end of the protein. Escherichia coli cells were transformed with an expression vector containing a major part of the bbp gene fused to the gene for glutathione S-transferase. The affinity-purified fusion protein bound radiolabelled native BSP, and inhibited the binding of radiolabelled BSP to staphylococcal cells. Serum from patients suffering from bone and joint infection contained antibodies that reacted with the fusion protein of the BSP-binding protein, indicating that the protein is expressed during an infection and is immunogenic. The S. aureus Bbp protein may be important in the localization of bacteria to bone tissue, and thus might be of relevance in the pathogenicity of osteomyelitis.

DNA Macroarray for Identification and Typing of Staphylococcus aureus Isolates

“…However, when only the 11 genes encoding putative adhesins were taken into account, the higher prevalence of sdrD in BI isolates than in NC isolates became significant. Some SD proteins were shown to bind fibrinogen (ClfA [21], ClfB [25], and SdrG [16]) or bone sialoprotein (Bbp) (33), but the ability of SdrD to bind a matrix protein(s) has not been investigated. The impact of sdrD inactivation merits evaluation in an animal model of BIs.…”

Structures of SdrD from Staphylococcus aureus reveal the molecular mechanism of how the cell surface receptors recognize their ligands

“…The detailed molecular mechanism of how the cell surface receptor-SdrD bind its ligand in S. aureus pathogenesis remains unknown (Tung et al, 2000). Trying to answer this question, we solved the high resolution crystal structures of SdrD N2- Particularly, the ligands of SdrD should contain a conserved SXGXXXT sequence in the centre.…”

Characterization of a Strain of Community-AssociatedMethicillin-Resistant Staphylococcus aureus WidelyDisseminated in the UnitedStates

“…Regarding cell surface components, USA300-0114 isolates contained all members of the capsule type 5 operon (cap5A to cap5P) and numerous adhesion genes, including clumping factor B (clfB) and clumping factor A (clfA) ( Table 3). The sdr loci encode proteins with similarity to clfA and clfB that are involved in binding fibrinogen and bone (69). Both sdrC and sdrE were present, although sdrD was not.…”