Characterization of a xhoi isoschizomer in streptomyces aureofaciens after actinophage infection

Abstract After infection of tetracycline producing strains of S. aureofaciens with actinophages μ1l / 6 and B1 some phage resistant colonies were obtained in each experiment. These colonies expressed a new restriction-modification (RM) system of type II, which was different from the common RM system ( Sau LPI) of these strains recognizing the sequence GCCGGC. This new RM system was not detected before in parental strains. The new endonuclease was purified from a phage resistant strain of S. aureofaciens B96, using two step column chromatography to the grade without non-specific nucleolytic activity. Sau LPII endonuclease recognized and cleaved the palindromic hexanucleotide sequence 5'-C/TCGAG-3', thus it was a true isoschizomer of Xho I.