Microbes as Intein Havens

Inteins are polypeptide escape artists, with an extraordinary ability to excise themselves from fully folded proteins without leaving a trace. Inteins are best described as protein introns, self-splicing elements that remove themselves posttranslationally from their host proteins. They occur in all three domains of life—archaea, bacteria, and single-celled eukaryotes (Fig. 1A). Even so, inteins are rarely discussed among microbiologists, but this relative silence is about to be broken.