Patent ID: 6852512

Claim:
A method for producing foreign proteins as soluble forms by using an N-terminal domain of an Escherichia coli lysS lysyl-tRNA synthetase as a fusion partner, comprising the steps of: a) transforming Escherichia coli with an expression vector that comprises (i) a polynucleotide sequence encoding said N-terminal domain of an Escherichia coli lysS lysyl-tRNA synthetase that is obtained by amplification of Escherichia coli genomic DNA using a pair of primers, wherein the primers have the structure of SEQ ID NO: 1 and SEQ ID NO:3, respectively, and (ii) a polynucleotide sequence encoding a protease recognition site, and a polynucleotide sequence encoding a foreign protein inserted in a polynucleotide sequence encoding a restriction enzyme recognition site, in due order; b) producing a fusion protein by culturing the transformant; c) recovering said fused protein from the culture; and d) cleaving said fusion protein with a protease.