Production of proteins

Abstract

The present invention relates to a process for the recombinant production of a desired heterologous polypeptide with a clearly defined homogenous N-terminus in a bacterial host cell. A fusion protein comprising a peptide with the autoproteolytic activity of an autoprotease N pro of a pestivirus and the heterologous polypeptide is initially expressed in the form of cytoplasmic inclusion bodies in the host cell, the inclusion bodies are isolated and subsequently treated so that the desired heterologous polypeptide is cleaved autoproteolytically by the N pro activity of the fusion protein.

1 . A process for the recombinant production of a heterologous polypeptide, comprising, (i) cultivation of a bacterial host cell which is transformed with an expression vector which comprises a nucleic acid molecule which codes for a fusion protein, the fusion protein comprising a first polypeptide which exhibits the autoproteolytic function of an autoprotease N pro  of a pestivirus, and a second polypeptide which is connected to the first polypeptide at the C-terminus of the first polypeptide in a manner such that the second polypeptide is capable of being cleaved from the fusion protein by the autoproteolytic activity of the first polypeptide, and the second polypeptde being a heterologous polypeptide, wherein cultivation occurs under conditions which cause expression of the fusion protein and formation of corresponding cytoplasmic inclusion bodies, 
 (ii) isolation of the inclusion bodies from the host cell,    (iii) solubilization of the isolated inclusion bodies,    (iv) dilution of the solubilizate to give a reaction solution in which the autoproteolytic cleavage of the heterologous polypeptide from the fusion protein is performed, and    (v) isolation of the cleaved heterologous polypeptide.    
     
     
         2 . A process according to  claim 1 , wherein the pestivirus is selected from the group of CSFV, BDV and BVDV.  
     
     
         3 . A process according to  claim 2 , wherein the pestivirus is CSFV.  
     
     
         4 . A process according to  claim 3 , wherein the first polypeptde comprises the following amino acid sequence:  
       
         
           
                 
                 
               
                     
                 
                   (1)-MELNHFELLYKTSKQKPVGVEEPVYDTAGRPLFGNPSEVHPQSTLKLPHDRGRGDIRTTLRDLPRKG 
                     
                 
                     
                 
                   DCRSGNHLGPVSGIYIKPGPVYYQDYTGPVYHRAPLEFFDEAQFCEVTKRIGRVTGSDGKLYHIYVCVDGC 
                 
                     
                 
                   ILLKLAKRGTPRTLKWIRNFTNCPLWVTSC-(168), 
                 
                     
                 
             
                
                
                
                
                
                
                
               
            
           
         
       
       or the amino acid sequence of a derivative thereof with autoproteolytic activity.  
     
     
         5 . A process according to  claim 3 , wherein the first polypeptde comprises the amino acid sequence Glu22 to Cys168 of the autoprotease N pro  of CSFV or a derivative thereof with autoproteolytic activity, wherein the first polypeptide has a Met as N-terminus, and wherein the heterologous polypeptide is directly connected to the amino acid Cys168 of the autoprotease N pro  of CSFV.  
     
     
         6 . A process according to  claim 3 , wherein the first polypeptide comprises the amino acid sequence Pro17 to Cys168 of the autoprotease N pro  of CSFV or a derivative thereof with autoproteolytic activity, wherein the first polypeptide has a Met as N-terminus, and wherein the heterologous polypeptide is directly connected to the amino acid Cys168 of the autoprotease N pro  of CSFV.  
     
     
         7 . A process according to  claim 1 , wherein the nucleic acid molecule is a DNA molecule.  
     
     
         8 . A process according to  claim 1 , wherein the expression vector is a plasmid.  
     
     
         9 . A process according to  claim 1 , wherein the bacterial host cell is an  E. coli  cell.