Protein splicing: its chemistry and biology.

Protein splicing is a chemical reaction in which a spliced intervening polypeptide is excised from a precursor protein and the flanking N- and C-terminal regions are ligated with the peptide bond to produce two mature proteins. This unique autocatalytic reaction was first discovered in the yeast VMA1 protein, a 120kDa spliced polypeptide encoded by the VMA1 gene of Saccharomyces cerevisiae. The VMA1 protein catalyses a self protein splicing post-translationally to yield the 70 kDa catalytic subunit of the vacuolar H+-ATPase and the 50 kDa DNA endonuclease. Accumulating evidence has indicated that splicing precursors distribute widely in many organisms covering eukarya, bacteria and archaea. This article argues and summarizes current chemical and biological views on protein splicing.