Method for Modifying a Property of a Protein

Abstract

A method for improving the thermostability of a protein includes introducing, into the protein, two or more amino acid substitutions selected from the group consisting of: (i) substitution of an arginine residue for a lysine residue, (ii) substitution of a threonine residue for a serine residue, and (iii) substitution of an alanine residue for a serine residue.

We claim: 
     
         1 . A method for improving thermostability of a protein, the method comprising introducing, into said protein, two or more amino acid substitutions selected from the group consisting of:
 (i) substitution of an arginine residue for a lysine residue,   (ii) substitution of a threonine residue for a serine residue, and   (iii) substitution of an alanine residue for a serine residue.   
     
     
         2 . The method according to  claim 1 , wherein said protein is a coryneform bacterium protein. 
     
     
         3 . The method according to  claim 2 , wherein said protein is a  Corynebacterium glutamicum  protein. 
     
     
         4 . A method for producing a protein having a modified thermostability, the method comprising:
 (a) introducing two or more amino acid substitutions into a gene encoding a protein, wherein the two or more amino acid substitutions are selected from the group consisting of:
 (i) substitution of an arginine residue for a lysine residue, 
 (ii) substitution of a threonine residue for a serine residue, and 
 (iii) substitution of an alanine residue for a serine residue; and 
   (b) introducing said gene obtained in (a) into a suitable host for gene expression to express the protein having the modified thermostability.   
     
     
         5 . The method according to  claim 4 , wherein said protein is a coryneform bacterium protein. 
     
     
         6 . The method according to  claim 5 , wherein said protein is a  Corynebacterium glutamicum  protein. 
     
     
         7 . A method for producing a microorganism having a modified thermostability, the method comprising introducing two or more amino acid substitutions into a chromosomal DNA of a microorganism to modify a thermostability of the microorganism, wherein said two or more amino acid substitutions are selected from the group consisting of:
 (i) substitution of an arginine residue for a lysine residue,   (ii) substitution of a threonine residue for a serine residue, and   (iii) substitution of an alanine residue for a serine residue.   
     
     
         8 . The method according to  claim 7 , wherein said microorganism is coryneform bacterium. 
     
     
         9 . The method according to  claim 8  wherein said microorganism is  Corynebacterium glutamicum.