Fibrinogen binding protein: Difference between revisions
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'''Efb function''' is a protein that is secreted by Staphylococcous Aureus which mimics the natural proteins in the body that inhibit the complement system. These proteins are called regulator of complement activation(RCA). In general, RCA proteins suppress the activation of C3 and C4 by dissociating the subunits of C3 and/or C5 convertases or by acting as cofactors for factor I–dependent cleavage of C3b and/or C4b. <ref>PMID: 17351618</ref> Efb has been shown to bind to the C3d domain of C3 and C3B, inhibiting its function. | '''Efb function''' is a protein that is secreted by Staphylococcous Aureus which mimics the natural proteins in the body that inhibit the complement system. These proteins are called regulator of complement activation(RCA). In general, RCA proteins suppress the activation of C3 and C4 by dissociating the subunits of C3 and/or C5 convertases or by acting as cofactors for factor I–dependent cleavage of C3b and/or C4b. <ref>PMID: 17351618</ref> Efb has been shown to bind to the C3d domain of C3 and C3B, inhibiting its function. | ||
<StructureSection load=' | <StructureSection load='2gox' size='350' side='right' caption='Structure of Efb (PDB entry [[2gox]])' scene=''> | ||
==Structural motifs== | ==Structural motifs== | ||
The overall dimensions of Efb-C were approximately 40x25x20 A° and 15.6 kDa, with the N-terminal a1 helix (K106–H125) connected | The overall dimensions of Efb-C were approximately 40x25x20 A° and 15.6 kDa, with the N-terminal a1 helix (K106–H125) connected | ||
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==Interactions== | ==Interactions== | ||
Two amino acids of Efb were noted as extremely important in achieving binding with the C3d domain, R131 and N138. Mutations by site -directed mutagenesis to these two points showed lack of complex formation and showed that other residues of Efb were not enough to drive complex formation. It was also observed that the a2 helix was mostly interacting with the C3d complex.<br> | Two amino acids of Efb were noted as extremely important in achieving binding with the C3d domain, <scene name='Extra_cellular_fibrinogen_binding_protein/R131/1'>R131</scene> and N138. Mutations by site -directed mutagenesis to these two points showed lack of complex formation and showed that other residues of Efb were not enough to drive complex formation. It was also observed that the a2 helix was mostly interacting with the C3d complex.<br> | ||
Efb-C blocks the formation of the functional C3b opsonin by binding tightly to the thioester-containing domain of native C3 and by perturbing the overall solution conformation of the molecule to one that is incapable of being processed into C3b. <ref>PMID: 17351618</ref> | Efb-C blocks the formation of the functional C3b opsonin by binding tightly to the thioester-containing domain of native C3 and by perturbing the overall solution conformation of the molecule to one that is incapable of being processed into C3b. <ref>PMID: 17351618</ref> | ||
