Identification and characterization of a cyanobacterial DnaX intein

A new intein is identified and characterized in the DnaX protein of Synechocystis sp. PCC6803. This cyanobacterial DnaX protein is a homologue of the intein-less 71-kDa tau-subunit of Escherichia coli DNA polymerase III and is related to eukaryotic DNA replication factor C (RFC). The 430-residue DnaX intein contains several putative intein sequence motifs and undergoes protein splicing when produced in E. coli cells. Its position in the DnaX protein is close to, but different from, positions of three inteins present in a DnaX-related RFC protein of Methanococcus jannaschii.