Identification of truncated E. coli-expressed proteins with a novel C-terminal 10Sa RNA decapeptide extension

Publisher Summary This chapter discusses the identification of truncated Escherichia coli ( E. coli )-expressed proteins with a novel C-terminal l0Sa RNA decapeptide extension. The recombinant proteins produced in E. coli are an important source of material for use as therapeutic drugs or reagents for structure–function relationship studies. Many of the biosynthetic proteins contain structural modifications that restrict their usefulness. The structural modifications include N- and C-terminal truncations extensions, incomplete removal of N-terminal initiator methionine, trisulfide derivatives, ɛ-N-acetyllysine, misincorporation of norleucine for methionine, and lysine for arginine. The chapter suggests that formation of recombinant protein-“tag” peptide chimeras is dependant on the l0Sa RNA gene. The mIL-6-“tag” peptide chimera mRNA transcripts or the presence in E. coli of the l0Sa RNA peptide product or precursor protein were not detected, thus, the biochemical mechanism underlying the fusion of the IL-6 and the translated l0Sa RNA peptide must involve a hitherto undescribed biochemical process.