Specific binding of the human S protein (vitronectin) to streptococci, Staphylococcus aureus, and Escherichia coli

Abstract

Specific binding of the 1251-labeled human S protein (vitronectin) which has been shown to be identical with serum-spreading factor, was observed with group A, C, and G streptococci as well as with Staphylococcus aureus and Escherichia coli. The specific binding of S protein to group A, C, and G streptococci was high, whereas the binding to S. aureus and E. coli cultures was moderate. In contrast, group B streptococci and a number of other bacterial species tested did not interact with S protein. The binding of S protein to bacteria was saturable and could be inhibited only by unlabeled S protein but not by albumin. Trypsinization and heat treatment of bacteria destroyed the S-protein binding capacity for group G streptococci, S. aureus, and E. coli but not for group A and C streptococci. Likewise, unlabeled human fibronectin and heparin inhibited the binding of labeled S protein to group G streptococci, S. aureus, and E. coli, but did not influence the binding to group A and C streptococci. Double-reciprocal plots of S-protein binding to group G streptococci indicated that fibronectin inhibited the binding in a, competitive manner, while heparin acts in a noncompetitive manner. Moreover, the binding of S protein to G streptococci could be partially inhibited by the synthetic peptide Gly-Arg-Gly-Asp-Ser, which contains the cell attachment site of S protein. Trypsin-treated S protein had similar binding activity as untreated S protein for group G streptococci, S. aureus, and E. coli, but showed reduced binding to group A and C streptococci. The present data are indicative of two different types of bacterial binding sites in S protein. The binding to group G streptococci, S. aureus, and E. coli is mediated in part through a domain in the S protein containing the sequence Arg-Gly-Asp, whereas a different site is responsible for the binding to group A and C streptococci.

Binding of vitronectin and plasminogen to Helicobacter pylori

“…Common pathogens of surgical wound infections such as Staphylococcus aureus and group A, 31 C and G streptococci, interact by specific surface proteins with a number of extracellular matrix (ECM) proteins such as fibronectin, various collagens, laminin and vitronectin [12][13][14]. Interestingly these pathogens also interact with several proteins involved in the blood clotting cascade such as fibrinogen, fibrin, plasminogen and vitronectin.…”

“…Vitronectin promotes attachment and spreading of eucaryotic cells, and is involved in immunological reactions such as inhibiting cell lysis by the complement system [9,11]. Surface receptors for vitronectin have been found on various cells such as platelets, endothelial cells and melanoma cells, and some bacterial pathogens [9,[12][13][14][15]. A specific interaction between vitronectin and plasminogen has been localized to the heparin binding domain [16].…”

Conditional adherence of Enterococcus faecalis to extracellular matrix proteins

“…Pathogenic streptococci have been found to bind to various ECM proteins including laminin [13], ¢bronectin [14], ¢brinogen [15], and collagen [16]. Staphylococcus aureus may express several surface components for binding to collagen [17], ¢bronectin [18,19], ¢brinogen [20], vitronectin [21], thrombospondin [22], elastin [23], laminin [24] and bone sialoprotein [25]. Mutants of pathogenic streptococci and staphylococci isogenic except for MSCRAMM genes have shown reduced virulence in arthritis and infective endocarditis models [26,27].…”

Role of α2-macroglobulin in phagocytosis of group A and C streptococci

“…a2M and a2M-T were radiolabeled by the chloramin T method [6] with specific activities of 1.2 and 0.9 mCi/mg, respectively. Assays were conducted in duplicates with 4 × 107 streptococci of each strain and 10 ng of 12sI-iabeled proteins in 0.15 M phosphate-buffered saline, pH 7.5 containing 0.05% Tweeh 20 [10]. After incubation for 1 h at room temperature the radioactivity associated with the sedimented streptococci was measured and expressed as percentage of the total radioactivity used for each assay.…”