Fusion proteins and polynucleotides encoding gelonin sequences

Abstract

The present invention provides purified and isolated polynucleotides encoding Type I ribosome-inactivating proteins (RIPS) and analogs of the RIPs having a cysteine available for disulfide bonding to targeting molecules. Vectors comprising the polynucleotides and host cells transformed with the vectors are also provided. The RIPs and RIP analogs are particularly suited for use as components of cytotoxic therapeutic agents of the invention which include gene fusion products and immunoconjugates. Cytotoxic therapeutic agents or immunotoxins according to the present invention may be used to selectively eliminate any cell type to which the RIP component is targeted by the specific binding capacity of the second component of the agent, and are suited for treatment of diseases where the elimination of a particular cell type is a goal, such as autoimmune disease, cancer and graft-versus-host disease.

1 . A fusion protein comprising (a) a gelonin amino acid sequence that has enzymatic activity and (b) a targeting sequence that allows the internalization of said fusion protein, wherein said targeting sequence is an antibody, an antigen-binding portion of an antibody, a hormone, a lymphokine or a growth factor.  
     
     
         2 . The fusion protein of  claim 1 , wherein said gelonin sequence is that of SEQ Id no. 2.  
     
     
         3 . The fusion protein of  claim 1 , wherein said gelonin sequence is that of SEQ ID NO. 101.  
     
     
         4 . The fusion protein of  claim 1 , further comprising a linker sequence between said gelonin sequence and said targeting sequence, wherein said gelonin possesses enzymatic activity, said antibody is capable of recognizing antigen and said hormone, lymphokine or growth factor is capable of binding to a cell that has a receptor for said hormone lymphokine or growth factor.  
     
     
         5 . The fusion protein of  claim 4 , wherein said linker sequence is that of SEQ ID NO. 56 or SEQ ID NO. 57.  
     
     
         6 . The fusion protein of any one of claim  1 - 5 , wherein said targeting sequence is an antibody.  
     
     
         7 . The fusion protein of any one of claims  1 - 5 , wherein said targeting sequence is an antigen-binding portion of an antibody.  
     
     
         8 . The fusion protein of  claim 7 , wherein said antigen-binding portion of said antibody is an Fab.  
     
     
         9 . The fusion protein of  claim 7 , wherein, wherein said antigen-binding portion of said antibody is an Fab′.  
     
     
         10 . The fusion protein of  claim 7 , wherein said antigen-binding portion of said antibody is an F(ab′) 2 .  
     
     
         11 . The fusion protein of  claim 7 , wherein said antigen-binding portion of said antibody is an Fv.  
     
     
         12 . The fusion protein of  claim 7 , wherein said antigen-binding portion of said antibody has a single variable domain.  
     
     
         13 . The fusion protein of  claim 7 , wherein said antibody is a single-chain antibody.  
     
     
         14 . The fusion protein of  claim 7 , wherein said fusion protein is multivalent.  
     
     
         15 . The fusion protein of any one of claims  1 - 5 , wherein said targeting sequence is a hormone.  
     
     
         16 . The fusion protein of any one of claims  1 - 5 , wherein said targeting sequence is a lymphokine.  
     
     
         17 . The fusion protein of any one of claims  1 - 5 , wherein said targeting sequence is a growth factor.