Proteintrans-splicing by a split intein encoded in a split DnaE gene ofSynechocystissp. PCC6803

Abstract

A split intein capable of proteintrans-splicing is identified in a DnaE protein of the cyanobacteriumSynechocystissp. strain PCC6803. The N- and C-terminal halves of DnaE (catalytic subunit α of DNA polymerase III) are encoded by two separate genes,dnaE-nanddnaE-c, respectively. These two genes are located 745,226 bp apart in the genome and on opposite DNA strands. ThednaE-nproduct consists of a N-extein sequence followed by a 123-aa intein sequence, whereas thednaE-cproduct consists of a 36-aa intein sequence followed by a C-extein sequence. The N- and C-extein sequences together reconstitute a complete DnaE sequence that is interrupted by the intein sequences inside the β- and τ-binding domains. The two intein sequences together reconstitute a split mini-intein that not only has intein-like sequence features but also exhibited proteintrans-splicing activity when tested inEscherichia colicells.