Motif-grafted hybrid polypeptides and uses thereof

Abstract

Provided herein are hybrid polypeptides that specifically bind to a disease-associated isoform of a polypeptide involved in diseases of protein aggregation. The hybrid polypeptides can be used for diagnosis and treatment of such diseases. In a particular embodiment, a hybrid protein that specifically binds to the infectious form of a prion (PrP Sc ) is provided.

1 . A hybrid polypeptide, comprising:
 a) a polypeptide motif from a polypeptide associated with a disease of protein aggregation or conformation; wherein:   the polypeptide associated with a disease of protein aggregation exists in at least one benign conformation and one infectious or aggregating conformation;   the motif participates in the interaction of the benign form with the aggregating form of the polypeptide or in the aggregation reaction;   the polypeptide motif contains a sufficient number of contiguous amino acid residues from the polypeptide associated with a disease of protein aggregation, presented in its native non-infectious conformation, whereby the hybrid polypeptide binds to the infectious conformer; and   b) a scaffold comprising at least 10 amino acids from a polypeptide other than the polypeptide from which the motif is derived, wherein:   the polypeptide motif is inserted into the scaffold or is linked to the scaffold; and   the resulting hybrid polypeptide binds with greater affinity to the infectious or aggregating conformer of the polypeptide associated with a disease of protein aggregation than to the benign form.   
     
     
         2 . The hybrid polypeptide of  claim 1 , wherein the polypeptide associated with a disease of protein aggregation is selected from among a prion, APP, Aβ, α1-antichymotrypsin, tau, non-Aβ component, presenilin 1, presenilin 2, apoE, superoxide dismutase (SOD) and neurofilament, Pick body, α-synuclein, tau in fibrils, amylin, IgGL-chain, transthyretin, procalcitonin, β 2 -microglobulin, atrial natriuretic factor, serum amyloid A, ApoAI, gelsolin and Huntington protein. 
     
     
         3 . The hybrid polypeptide of  claim 1  that is multimeric. 
     
     
         4 . The hybrid polypeptide of  claim 1  that is a dimer or a trimer. 
     
     
         5 . The hybrid polypeptide of  claim 1 , wherein the scaffold comprises at least 5 amino acids at the N-terminus and at least 5 amino acids at the C-terminus of the motif portion. 
     
     
         6 . The hybrid polypeptide of  claim 1  that contains at least 20 contiguous amino acid residues from the polypeptide associated with a disease of protein aggregation. 
     
     
         7 . The hybrid polypeptide of  claim 1 , wherein the scaffold comprises all or a portion of a protein selected from among an antibody, enzyme, chromogenic protein or fluorescent protein, sufficient to present the polypeptide motif in its native non-infectious conformation. 
     
     
         8 . The hybrid polypeptide of  claim 1 , wherein the scaffold is an immunoglobulin or a fragment thereof. 
     
     
         9 . The hybrid polypeptide of  claim 8 , wherein the scaffold is an Fab, an F(ab) 2  or single chain Fv. 
     
     
         10 . The hybrid polypeptide of  claim 1 , wherein the scaffold is an immunoglobulin or fragment thereof and the motif is inserted within the third complementarity-determining region (CDR) of the immunoglobulin molecule. 
     
     
         11 . The hybrid polypeptide of  claim 1 , wherein the disease is selected from among Creutzfeldt-Jakob disease, scrapie and bovine spongiform encephalopathy, Alzheimer's Disease, Type II Diabetes, Huntington's Disease, immunoglobulin amyloidosis, reactive amyloidosis associated with chronic inflammatory disease, hereditary systemic amyloidosis associated with autosomal dominant inheritance of variant transthyretin gene, ALS, Pick's Disease, Parkinson's disease, Frontotemporal dementia, Diabetes Type II, Multiple myeloma, Plasma cell dyscrasias, Familial amyloidotic polynueuropathy, Medullary carcinoma of thyroid; chronic renal failure, congestive heart failure, senile cardiac and systemic amyloidosis, chronic inflammation, atherosclerosis and familial amyloidosis. 
     
     
         12 . The hybrid polypeptide of  claim 1 , wherein the polypeptide motif is from a prion protein. 
     
     
         13 . The hybrid polypeptide of  claim 12 , wherein the polypeptide motif comprises contiguous residues from a portion of the prion protein that corresponds to residues 87-169 of the Syrian hamster prion polypeptide having a sequence set forth in SEQ ID NO:5 or corresponding residues from a prion from another species. 
     
     
         14 . A nucleic acid molecule encoding the hybrid polypeptide of  claim 1 . 
     
     
         15 . A vector, comprising the nucleic acid molecule of  claim 14 . 
     
     
         16 . A cell, comprising the vector of  claim 15 . 
     
     
         17 . A method of detecting an infectious conformer of a polypeptide associated with a disease of protein aggregation, comprising:
 contacting a sample suspected of containing the infectious conformer with the hybrid polypeptide of  claim 1 , wherein the hybrid polypeptide is detectably labeled or the scaffold is detectable; and   detecting binding of the hybrid polypeptide to the infectious conformer.   
     
     
         18 . The method of  claim 17 , wherein the sample selected is from among a body fluid, tissue and organs. 
     
     
         19 . The method of  claim 17 , wherein the sample contains cells.