Structural and functional analysis of an anchorless fibronectin-binding protein FBPS from Gram-positive bacterium Streptococcus suis

Abstract

The anchorless fibronectin-binding proteins (FnBPs) are a group of important virulence factors for which the structures are not available and the functions are not well defined. In this study we performed comprehensive studies on a prototypic member of this group: the fibronectin-/fibrinogen-binding protein from Streptococcus suis (FBPS). The structures of the N-and C-terminal halves (FBPS-N and FBPS-C), which together cover the full-length protein in sequence, were solved at a resolution of 2.1 and 2.6 Å, respectively, and each was found to be composed of two domains with unique folds. Furthermore, we have elucidated the organization of these domains by small-angle X-ray scattering. We further showed that the fibronectin-binding site is located in FBPS-C and that FBPS promotes the adherence of S. suis to host cells by attaching the bacteria via FBPS-N. Finally, we demonstrated that FBPS functions both as an adhesin, promoting S. suis attachment to host cells, and as a bacterial factor, activating signaling pathways via β1 integrin receptors to induce chemokine production.fibronectin-binding protein of Streptococcus suis | structure | novel fold | fibronectin-binding property | function

Mapping the recognition domains of pneumococcal fibronectin‐binding proteins PavA and PavB demonstrates a common pattern of molecular interactions with fibronectin type III repeats

“…The different binding behaviour between PavA and PavA 42 could thus lie in the C‐terminal 186 residues or in an improperly folded helix of PavA 42 . FBPS of S. suis interacts via its C‐terminal part FBPS‐C with the N‐terminal 30 kDa part of Fn when used in micromolar concentrations in surface plasmon resonance studies (Musyoki et al ., ). FBPS‐N did not bind to the N‐terminal part of Fn.…”

“…Strikingly, exogenously added recombinant PavA (rPavA) restores the wild type in a pavA ‐mutant and pavA ‐mutants covered with rPavA escape phagocytosis and induce a cytokine profile similar to wild‐type pneumococci (Noske et al ., ). FBPS, a homologue of PavA with 74% identity, reveals an α/β and an α domain in its N‐terminal half and an α domain with two very long helices and an α/β domain in its C‐terminal half (Musyoki et al ., ).…”

Molecular Basis of a Protective/Neutralizing Monoclonal Antibody Targeting Envelope Proteins of both Tick-Borne Encephalitis Virus and Louping Ill Virus

“…We used the full-length protein (552 amino acids) for crystallization trials. However, the crystals unexpectedly contained only the N-terminal 267 amino acids (S2 to K268) (53). Another example is from the crystal structure of the transmembrane protein MCR-2 expressed in E. coli (PDB accession number 6A7W).…”

The non-conserved region of MRP is involved in the virulence ofStreptococcus suisserotype 2

“…Previous studies have demonstrated that SS surface proteins can bind different host components of human extracellular matrix or serum proteins, including FN, [13][14][15][16]33 FH, 19,34 FG, 8 and IgG. 35,36 These proteins play various roles in the adhesion, invasion, physiology, and immune escape of the bacteria via different mechanisms, which cooperatively contribute to the full virulence of SS.…”

“…HEp-2 cell pull-down assays were performed as described previously with minor modification. 33 Briefly, the cells were collected and washed twice with PBS, and then incubated with 100 mg/ml of purified recombinant MRP-D1, MRP-D1 Ã , MRP-D2, HP07325 or BSA for 2 h at 37 C. The cells were harvested by centrifugation and washed twice in PBS. Then, the cell pellets were boiled and separated by SDS-PAGE, and the gels were transferred to PVDF membranes for Western blotting with an anti-His tagged monoclonal antibody as described above.…”