Crystal Structure of Staphylococcus Aureus Clumping Factor A in Complex with Fibrinogen Derived Peptide and Uses Thereof

Abstract

The present invention discloses crystal structure of Staphylococcus aureus Clumping factor A (ClfA) in complex with fibrinogen (Fg) derived peptide. Also, the present invention also discloses the use of this structure in the design of ClfA targeted vaccines and therapeutic agents (including monoclonal antibodies). In addition, the present invention discloses isolated and purified engineered Staphylococcus clumping factor A protein (ClfA) with a stabilized, closed conformation and immunogenic compositions thereof including methods of treating a Staphylococcus infection in an individual.

What is claimed is: 
     
         1 . A crystal structure of a  Staphylococcus  clumping factor A protein (ClfA):fibrinogen derived peptide complex that diffracts x-rays for determining atomic coordinates of the complex with a resolution of at least about 2 angstroms. 
     
     
         2 . The crystal structure of  claim 1 , wherein the ClfA is a sequence homolog, functional homolog or both. 
     
     
         3 . The crystal structure of  claim 1 , wherein molecular interactions are identified for ClfA residues 521-529 and fibrinogen. 
     
     
         4 . The crystal structure of  claim 1 , wherein
 residues 522, 524, 526 and 528 are involved in mainchain-mainchain hydrogen bonding interaction;   side chain of Trp523 is involved in anchoring the gamma chain of fibrinogen;   side chain of Asn525 is involved in hydrogen bonding interaction with Gln408 of fibrinogen;   residue 521 has hydrophobic interaction with gamma chain of fibrinogen;   residue 526 does not have any side chain interaction with fibrinogen and may not be a key residue in fibrinogen binding;   residue 528 does not have any side chain interaction with fibrinogen and may not be a key residue in fibrinogen gamma chain binding; or   residue 529 has hydrophobic interaction with glycine residue 409 in the gamma chain of fibrinogen.   
     
     
         5 . A therapeutic agent comprising a binding agent that
 (1) disrupts interaction at residues 521 to 529 of a clumping factor A protein (ClfA) with a gamma chain of a fibrinogen;   (2) disrupts interaction at residues 505-513 in Fbl with a gamma chain of a fibrinogen; or   (3) disrupts interaction at residues 492-500 in FnbpA with a gamma chain of a fibrinogen, wherein the binding agent is a monoclonal antibody, small molecule, or peptide   
     
     
         6 . A therapeutic agent that blocks the interaction of microbial surface components recognizing adhesive matrix molecules (MSCRAMMs) with fibrinogen comprising:
 a therapeutic agent with at least 85% homology to residues 521-529 of ClfA; residues 492-500 of Fbl; residues 505-513 of FnbpA or a combination thereof, wherein the therapeutic agent reduces MSCRAMMs interactions with a gamma chain of a fibrinogen   
     
     
         7 . The therapeutic agent of  claim 6 , wherein the residues 521-529 of ClfA are involved in either mainchain-mainchain interaction or interactions involving side chains. 
     
     
         8 . The therapeutic agent of  claim 6 , wherein the therapeutic agent supports both a fibrinogen gamma chain binding and maintains a structural fold by maintaining a B-sheet with a N3 domain. 
     
     
         9 . The therapeutic agent of  claim 6 , wherein the therapeutic agent has at least 85% homology to residues 521-529 of ClfA and residues 522, 524, 526 and 528 are involved in mainchain-mainchain hydrogen bonding interaction. 
     
     
         10 . The therapeutic agent of  claim 6 , wherein the therapeutic agent has at least 85% homology to residues 521-529 of ClfA and a side chain of Trp523 is involved in anchoring the gamma chain of fibrinogen. 
     
     
         11 . The therapeutic agent of  claim 6 , wherein the therapeutic agent has at least 85% homology to residues 521-529 of ClfA and a side chain of Asn525 is involved in hydrogen bonding interaction with Gln408 of fibrinogen. 
     
     
         12 . The therapeutic agent of  claim 6 , wherein the therapeutic agent has at least 85% homology to residues 521-529 of ClfA and residue 521 has hydrophobic interaction with a gamma chain of a fibrinogen. 
     
     
         13 . The therapeutic agent of  claim 6 , wherein the therapeutic agent has at least 85% homology to residues 521-529 of ClfA and residue 526 does not have any side chain interaction with a fibrinogen and may not be a key residue in fibrinogen binding. 
     
     
         14 . The therapeutic agent of  claim 6 , wherein the therapeutic agent has at least 85% homology to residues 521-529 of ClfA and residue 528 does not have any side chain interaction with fibrinogen and may not be a key residue in fibrinogen gamma chain binding. 
     
     
         15 . The therapeutic agent of  claim 6 , wherein the therapeutic agent has at least 85% homology to residues 521-529 of ClfA and residue 529 has a hydrophobic interaction with a glycine residue 409 in a gamma chain of a fibrinogen. 
     
     
         16 . The therapeutic agent of  claim 6 , wherein the therapeutic agent has at least 85% homology to residues 521-529 of ClfA and further comprises a hydrophobic interactions with an alanine residue 401 in a gamma chain of a fibrinogen. 
     
     
         17 . The therapeutic agent of  claim 6 , wherein the therapeutic agent is homologous to MSWDNEVAF, MAWDNEVEY, or LTWDNGLVLY. 
     
     
         18 . A method of identifying and targeting gamma chain binding MSCRAMMs/bacterial proteins comprising the steps of:
 providing a crystal structure of a clumping factor A protein (ClfA):fibrinogen derived peptide complex;   
       providing a targeting sequence to identify the fibrinogen gamma chain binding target. 
     
     
         19 . The method of  claim 18 , wherein the targeting sequence is homologous to residues 521-529 of ClfA. 
     
     
         20 . The method of  claim 18 , wherein the targeting sequence is homologous to residues 492-500 of Fbl. 
     
     
         21 . The method of  claim 18 , wherein the targeting sequence is homologous to residues 505-513 of FnbpA. 
     
     
         22 . The method of  claim 18 , wherein the targeting sequence is homologous to MSWDNEVAF, MAWDNEVEY, or LTWDNGLVLY.