[Protein splicing and its application].

Protein splicing is a newly discovered posttranslational editing process that removes an internal protein fragment from the protein precursor. During the splicing process the internal protein fragment, intein, triggered the self-excision from the precursor protein and the concomitant ligation of the flanking protein fragments, exteins. The self-catalysis requires neither auxiliary enzymes nor cofactors and only involves four intramolecular reactions. A number of key catalytic residues in inteins and flanking fragments have been identified, which led to the development of the protein splicing process as a protein engineering tool. Controllable cleavage of the peptide bond at either the N or the C terminus of an intein has allowed the design of novel strategies for manipulation of protein and peptides. Affinity purification of recombinant proteins can be facilitated by fusion the target protein with an intein. The fusion also creates C-terminal thioester, which expands the scope of chemical ligation in protein. Inteins can be engineered in a "split and inverted" configuration to form a cyclic polypeptide consisting of the sequence linking two intein subdomains. This article summarizes the recent advance in the mechanism of protein splicing and its applications in protein purification, protein ligation and protein cyclization.