intein-mediated protein splicing

Definition

Target type: biologicalprocess

The removal of an internal amino acid sequence (an intein) from a protein during protein maturation; the excision of inteins is precise and the N- and C-terminal exteins are joined by a normal peptide bond. Protein splicing involves 4 nucleophilic displacements by the 3 conserved splice junction residues. [GOC:ma, http://www.neb.com/neb/inteins.html]

Intein-mediated protein splicing is a remarkable post-translational process where a protein segment, known as an intein, excises itself from a precursor protein, simultaneously ligating the flanking protein segments (exteins) to form a mature protein. This process is highly specific and efficient, occurring without the need for external enzymes or cofactors.

The intein, often referred to as a protein "parasite," is typically located within a larger protein, often possessing a catalytic domain with endonuclease and ligase activities. The splicing process unfolds in a series of precisely orchestrated steps involving the formation of a transient, branched intermediate.

1. **Recognition and Cleavage:** The intein recognizes specific amino acid residues at its N- and C-termini, typically asparagine (N) and a hydrophobic residue like alanine (A). These residues define the splicing junctions. The intein's catalytic domain then cleaves the peptide bond between the intein's N-terminus and the upstream extein.

2. **Branch Formation:** The cleaved N-terminal extein forms a new peptide bond with the intein's active site, creating a branched intermediate. This intermediate is a key feature of intein-mediated splicing, as it provides the necessary structural framework for subsequent steps.

3. **Transesterification:** The intein's catalytic domain then catalyzes a transesterification reaction, transferring the C-terminal extein from the intein's C-terminus to the N-terminus of the upstream extein. This step effectively joins the two exteins together.

4. **Excision and Ligation:** The intein is now excised from the protein chain, leaving behind a mature protein with the two exteins joined at the original splicing site. The excised intein is typically degraded or otherwise removed from the cell.

Intein-mediated protein splicing has gained significant attention in biotechnology due to its potential applications in protein engineering, biomaterials, and diagnostics. This process allows researchers to precisely control the cleavage and ligation of proteins, enabling the creation of novel proteins with enhanced functionalities or the removal of unwanted protein segments. Furthermore, inteins can be used as molecular tags for protein purification or as probes for studying protein folding and interactions. The study of intein-mediated protein splicing continues to unravel new insights into protein dynamics and offers exciting avenues for future biotechnological applications.'
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Proteins (1)

Compounds (5)