The Inducible Intein-Mediated Self-Cleaving Tag (IIST) System: A Novel Purification and Amidation System for Peptides and Proteins

An efficient self-cleavable purification tag could be a powerful tool for purifying recombinant proteins and peptides without additional proteolytic processes using specific proteases. Thus, the intein-mediated self-cleavage tag was developed and has been commercially available as the IMPACT (TM) system. However, uncontrolled cleavages of the purification tag by the inteins in the IMPACT (TM) system have been reported, thereby reducing final yields. Therefore, controlling the protein-splicing activity of inteins has become critical. Here we utilized conditional protein splicing by salt conditions. We developed the inducible intein-mediated self-cleaving tag (IIST) system based on salt-inducible protein splicing of the MCM2 intein from the extremely halophilic archaeon, Halorhabdus utahensis and applied it to small peptides. Moreover, we described a method for the amidation using the same IIST system and demonstrated N-15-labeling of the C-terminal amide group of a single domain antibody (V-HH).

Automated summary

This study introduces an IIST system based on salt-inducible conditional protein splicing using the intein from Halorhabdus utahensis for purification of small peptides. It also describes a method for amidation and N-15 labeling of a single domain antibody using the same system.