Human plasma fibronectin possesses second binding site(s) to Staphylococcus aureus on its C-terminal region.
The existence of a second binding site to Staphylococcus aureus on fibronectin was explored by using a recombinant protein, alb-FnBPA, which was obtained from an Escherichia coli clone containing a part of the gene for fibronectin-binding protein of S. aureus. Limited digestion with trypsin produced a 215K fragment from the B chain of fibronectin by releasing an N-terminal 32 kDa region. This C-terminal large fragment captured alb-FnBPA in spite of lacking the N-terminal binding region to S. aureus. This treatment also produced a 185K fragment from A chain by releasing N-terminal 32 kDa and C-terminal 37 kDa regions, and the 185K fragment possessed no binding ability. Thermolysin digestion was also performed to investigate the effect on the binding of releasing the C-terminal region from both of the chains and to locate the binding region to alb-FnBPA on the tryptic 215K fragment. But this digestion produced no fragment binding to alb-FnBPA except for the N-terminal 24K and its transient precursory fragments. These results indicate that both the N-terminal and the C-terminal regions of fibronectin bind to S. aureus, and suggest that the binding appears to involve cooperation between type III repeats and C-terminal type I repeats.
Department of Medical Microbiology, University of Lund, Sweden.
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Sakata
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Jakab
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Wadström
D001665:Binding Sites; D005353:Fibronectins / Q000097:blood*; D006493:Heparin / Q000378:metabolism*; D006801:Humans; D010446:Peptide Fragments / Q000378:metabolism; D017434:Protein Structure, Tertiary; D013211:Staphylococcus aureus / Q000378:metabolism*; D014357:Trypsin
D005353:Fibronectins; D010446:Peptide Fragments; D006493:Heparin; D014357:Trypsin