Bacteriophage-based genetic system for selection of nonsplicing inteins

A genetic selection system that detects splicing and nonsplicing activities of inteins was developed based on the ability to rescue a T4 phage strain with a conditionally inactive DNA polymerase. This phage defect can be complemented by expression of plasmid-encoded phage RB69 DNA polymerase. Insertion of an intein gene into the active site of the RB69 DNA polymerase gene renders polymerase activity and phage viability dependent on protein splicing. The effectiveness of the system was tested by screening for thermosensitive splicing mutants. Development of genetic systems with the potential of identifying protein splicing inhibitors is a first step towards controlling proliferation of pathogenic microbes harboring inteins in essential proteins.