The N-Terminal A Domain of Staphylococcus aureus Fibronectin-Binding Protein A Binds to Tropoelastin

Abstract

Staphylococcus aureus is an important human pathogen. Its virulence factors include a variety of MSCRAMMs (microbial surface component recognizing adhesive matrix molecules), each capable of binding specifically to the host extracellular matrix. The fibronectin-binding protein, FnBPA, has been shown previously to bind immobilized fibronectin, fibrinogen, and alpha-elastin peptides. Here we show that region A of FnBPA (rAFnBPA) binds to recombinant human tropoelastin. Binding occurs to three separate truncates of tropoelastin, encompassing domains 2-18, 17-27, and 27-36, signifying that the interaction occurs at multiple sites. The greatest affinity was for the N-terminal truncate. We observed a pH dependency for the rAFnBPA-tropoelastin interaction with strong, nonsaturable binding at low pH. The interaction ceased at higher pH. These data support a model of surface-surface interactions between the negative charges present on rAFnBPA and the positive lysines of tropoelastin. A protein lacking the negatively charged C-terminal fibronectin-binding motif of the A domain of FnBPA and another construct lacking subdomain N1 were both capable of binding immobilized tropoelastin with a lower affinity. The binding properties of five site-directed mutants of rAFnBPA were compared with wild-type rAFnBPA. There was no decreased affinity for immobilized tropoelastin, in contrast to the defective binding of these mutants to alpha-elastin and fibrinogen. The data indicate novel interactions between tropoelastin and FnBPA that include the use of surface charges. These results demonstrate that FnBPA is capable of directly binding tropoelastin prior to its incorporation into elastin.

Elastin, a Novel Extracellular Matrix Protein Adhering to Mycobacterial Antigen 85 Complex

“…Our results indicated that all recombinant truncated human tropoelastin fragments (GST-HTE(1-18), GST-HTE (17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27), GST-HTE (27)(28)(29)(30)(31)(32)(33)(34)(35)(36), and GST-HTE(27-28)) bind to M. tuberculosis Ag85B with similar K D values (ϳ0.5 M) (Figs. 2B and 3B).…”

Relevant Role of Fibronectin-Binding Proteins in Staphylococcus aureus Biofilm-Associated Foreign-Body Infections

“…In their study, Bisognano et al showed that LexA is a repressor of fnbB expression, and consequently, SOS response induction by commonly used fluoroquinolones resulted in the increased expression of the FnBPB protein on the bacterial surface (7). As FnBPs have been shown to play an important role during invasion of mammalian cells (47,48) and in mediating adherence to different host extracellular matrix components, such as fibronectin, fibrinogen, elastin, or tropoelastin (23,43,55), an adverse consequence of SOS induction by antibiotics would be that it might facilitate colonization of host cells and medical implants (13,17). Accordingly, our results suggest that an increase in FnBPB expression through activation of the SOS response is sufficient to induce a noticeable increase in the capacity of the strain to produce multicellular communities on abiotic surfaces in vitro.…”

Repeated Domains of Leptospira Immunoglobulin-like Proteins Interact with Elastin and Tropoelastin

“…During the major phase of elastogenesis, multiple tropoelastin molecules associate through coacervation (30 -32). Because of the abundance of elastin or tropoelastin on the surface of host cells, several bacterial MSCRAMMs use elastin and/or tropoelastin to mediate adhesion during the infection process (33)(34)(35).…”