Restriction endonuclease PshAI from Plesiomonas shigelloides with the novel recognition site 5'-GACNN/NNGTC.

A new restriction endonuclease (ENase), PshAI, has been isolated from Plesiomonas shigelloides 319-73, an organism that causes food poisoning in humans. The enzyme was stable and produced a yield of 410 units/g of cells. In the presence of 10 mM MgCl2, PshAI recognizes and cleaves the nucleotide sequence 5'-GACNN/NNGTC, producing blunt ends. PshAI will be useful for structural analysis and molecular cloning of DNA, because no ENases recognizing sequence GACNNNNGTC have been previously described.