Staphylococcus aureus Fibronectin-Binding Protein Serves as a Substrate for Coagulation Factor XIIIa:  Evidence for Factor XIIIa-Catalyzed Covalent Cross-Linking to Fibronectin and Fibrin

Abstract

In this study, we have investigated the interactions of a Staphylococcal recombinant fibronectin-binding protein A (rFnbA) with fibronectin, fibrinogen, and fibrin. Using analytical size-exclusion chromatography, we evaluated the stoichiometry of reversible binding of FnbA to fibronectin and demonstrated that, in solution, it can accommodate at least two molecules of fibronectin. Results of ELISA experiments demonstrated that rFnbA binds with equally high affinity to both immobilized fibrinogen and fibrin. When included into a thrombin-induced fibrin polymerization reaction, rFnbA strongly inhibited fibrin assembly in a dose-dependent manner. In this study, we have shown that rFnbA can act as a substrate for coagulation factor XIIIa. Factor XIIIa catalyzes the incorporation of amine donor (dansylacadaverine) and amine acceptor (peptide patterned on the N-terminal sequence of fibronectin) synthetic probes into rFnbA, suggesting that it serves as a bifunctional substrate containing reactive glutamine and lysine residues. We have demonstrated that the reversible complex formed by rFnbA and fibronectin or rFnbA and fibrin is covalently stabilized by the transglutaminase action of factor XIIIa. Incubation of rFnbA in the presence of either of its ligands and factor XIIIa results in the introduction of intermolecular epsilon-(gamma-glutamyl)lysine isopeptide bond(s) and the formation of high molecular mass heteropolymers. These findings suggest a novel mechanism by which pathogenic Staphylococcus aureus may utilize the transglutaminase activity of factor XIIIa for attachment to soluble proteins, cell surfaces, and matrixes.

A Recombinant Clumping Factor A-Containing Vaccine Induces Functional Antibodies to Staphylococcus aureus That Are Not Observed after Natural Exposure

“…Significant levels of ClfB were not detected on the surfaces of the stationary-phase cells used in these experiments (not shown), an observation which is consistent with its expression primarily during the exponential phase of bacterial growth (31). We speculate that the apparent lack of interference in this in vitro assay by other known S. aureus Fgbinding adhesins such as FnbA (20,24) and Bbp (37) may be similarly due to the use of stationary-phase cells. The relevance of Fg binding to the pathology of S. aureus infection has been demonstrated in a mouse abscess model in which ClfA or ClfB null mutants show a significant bacterial load reduction (5).…”

Multiple Ligands of von Willebrand Factor-binding Protein (vWbp) Promote Staphylococcus aureus Clot Formation in Human Plasma

“…Finally, fibronectin-binding protein A (FnbpA), a surface protein expressed by most S. aureus strains, also serves as a substrate for factor XIIIa (51). At least in vitro, FnbpA is covalently cross-linked to both fibronectin and fibrin/fibrinogen (51).…”

Identification of TwoMycobacterium marinumLoci That Affect Interactions with Macrophages

“…can recruit transglutaminases from host cells to cross-link proteins in the cell leading to internalization of the bacteria (24), and Staphylococcus spp. appear to use transglutaminases for attachment to host proteins, which is believed to be important for colonization (28). However, insight into the potential functions of these transglutaminases is complicated by the fact that they are also usually proteases and that eukaryotic transglutaminases may have evolved from bacterial cysteine proteases (25).…”