Protein splicing involves the excision of an internal protein segment, the intein, from a
precursor protein and the concomitant ligation of the flanking N-and C-terminal regions. It
occurs in mesophilic bacteria, yeast, and thermophilic archaea. The ability to control protein
splicing of a thermophilic intein by temperature and pH in a foreign protein context facilitated
the study of the mechanism of protein splicing in thermophiles. On the other hand, no direct
studies have been done on the mechanism of protein splicing in mesophiles. We examined …