Ultrafast protein splicing is common among cyanobacterial split inteins: implications for protein engineering.

We describe the first systematic study of a family of inteins, the split DnaE inteins from cyanobacteria. By measuring in vivo splicing efficiencies and in vitro kinetics, we demonstrate that several inteins can catalyze protein trans-splicing in tens of seconds rather than hours, as is commonly observed for this autoprocessing protein family. Furthermore, we show that when artificially fused, these inteins can be used for rapid generation of protein α-thioesters for expressed protein ligation. This comprehensive survey of split inteins provides indispensable information for the development and improvement of intein-based tools for chemical biology.