The streptococcal binding site in the gelatin-binding domain of fibronectin is consistent with a non-linear arrangement of modules.
Fibronectin-binding proteins (FnBPs) of Staphylococcus aureus and Streptococcus pyogenes mediate invasion of human endothelial and epithelial cells in a process likely to aid the persistence and/or dissemination of infection. In addition to binding sites for the N-terminal domain (NTD) of fibronectin (Fn), a number of streptococcal FnBPs also contain an upstream region (UR) that is closely associated with an NTD-binding region; UR binds to the adjacent gelatin-binding domain (GBD) of Fn. Previously, UR was shown to be required for efficient streptococcal invasion of epithelial cells. Here we show, using a Streptococcus zooepidemicus FnBP, that the UR-binding site in GBD resides largely in the (8)F1(9)F1 module pair. We also show that UR inhibits binding of a peptide from the α1 chain of type I collagen to (8)F1(9)F1 and that UR binding to (8)F1 is likely to occur through anti-parallel β-zipper formation. Thus, we propose that streptococcal proteins that contain adjacent NTD- and GBD-binding sites form a highly unusual extended tandem β-zipper that spans the two domains and mediates high affinity binding to Fn through a large intermolecular interface. The proximity of the UR- and NTD-binding sequences in streptococcal FnBPs is consistent with a non-linear arrangement of modules in the tertiary structure of the GBD of Fn.
Atkin
Kate E
KE
Department of Biology, University of York, Heslington, York, YO10 5DD, United Kingdom.
Brentnall
Andrew S
AS
Harris
Gemma
G
Bingham
Richard J
RJ
Erat
Michele C
MC
Millard
Christopher J
CJ
Schwarz-Linek
Ulrich
U
Staunton
David
D
Vakonakis
Ioannis
I
Campbell
Iain D
ID
Potts
Jennifer R
JR
D000595:Amino Acid Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D005353:Fibronectins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005780:Gelatin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D018502:Streptococcus equi / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*
D005353:Fibronectins; D011994:Recombinant Proteins; D005780:Gelatin