In vivo production of cyclic peptides

Abstract

The present invention relates to methods and compositions utilizing inteins to generated libraries of cyclic peptides in vivo.

1 - 18 . (canceled)  
     
     
         19 . An isolated cell comprising: 
 a cyclic peptide consisting of four amino acids, wherein at least one of said amino acids is a Ser, Thr or Cys.    
     
     
         20 . The isolated cell of  claim 19 , wherein said cell further comprises: 
 a nucleic acid encoding a fusion protein comprising, in order: 
 a) a C-terminal intein domain;  
 b) a peptide; and  
 c) a N-terminal intein domain;  
 wherein said fusion protein undergoes a reaction to produce said cyclic peptide.  
   
     
     
         21 . The isolated cell of  claim 19 , wherein said cell is a mammalian cell.  
     
     
         22 . The isolated cell of  claim 20 , wherein said fusion protein is encoded by retroviral vector.  
     
     
         23 . The isolated cell of  claim 20 , wherein said cell is a mammalian cell.  
     
     
         24 . An isolated cell comprising a cyclic peptide consisting of four amino acids, wherein at least one of said amino acids is a Ser, Thr or Cys, and wherein said cyclic peptide is produced as a result of a cyclization reaction of a fusion protein comprising, in order: a) a C-terminal intein domain; b) a peptide; and c) a N-terminal intein domain.  
     
     
         25 . The isolated cell of  claim 24 , wherein said cell is a mammalian cell.  
     
     
         26 . The isolated cell of  claim 24 , wherein said fusion protein is encoded by retroviral vector.