Polypeptide factor from a thermophilic eubacterial species and use thereof in the production of functional, heterologous proteins in an expression host

Abstract

A polypeptide factor derived from the thermophilic eubacterial species Thermus thermophilus has universal protein expression-assisting activity. The polypeptide factor has been named the CzrB protein active in full length or truncated form has the potential to act as a universal protein expression-assisting molecule which can increase the yields of all heterologous proteins produced in E. coli by a mechanism that is independent of the protein being expressed.

1 .  E. coli  bacteria comprising a polypeptide factor from a thermophilic eubacterial species, wherein said polypeptide factor is a metal ion efflux protein, which assists in the expression of heterologous proteins and which confers on  E. coli  increased resistance to heavy metal ions compared to wild-type  E - coli  that do not contain the polypeptide factor.  
     
     
         2 . The  E. coli  bacteria of  claim 1 , wherein the thermophilic eubacterial species is  Thermus thermophilus.    
     
     
         3 . The  E. coli  bacteria of  claim 1 , wherein the polypeptide factor has an amino acid sequence as defined by amino acid position No. 1 to amino acid position No. 291 of SEQ ID NO:1.  
     
     
         4 . The  E. coli  bacteria of  claim 1 , wherein the polypeptide factor has an amino acid sequence of SEQ ID NO:2.  
     
     
         5 . A method of increasing the production of a heterologous protein in a bacterial host cell, which comprises cultivating the  E. coli  of  claim 1  under conditions that permit expression of the polypeptide factor by the  E. coli.    
     
     
         6 . The method of  claim 5 , wherein the heterologous protein is a eukaryotic protein.