A NEW THERMOPHILIC STRAIN OF BACILLUS-COAGULANS PRODUCING SITE-SPECIFIC ENDONUCLEASE BCOKI

A thermophilic bacterial strain producing a new site-specific endonuclease BcoKI was isolated from tobacco leaves. The phenotypic characterization of this strain, which was identified as a new strain of Bacillus coagulans, is presented. BcoKI, a class-IIS restriction endonuclease, was obtained by three successive chromatographic procedures employing blue agarose, hydroxyapatite, and heparin-Sepharose. BcoKI, an isoschizomer of Ksp6321 [1], recognizes a hexanucleotide non-palindromic sequence 5'-CTCTTC-3' and cleaves this strand at a distance of one nucleotide from the 3'-cytosine and the opposite strand, four nucleotides from the 5'-guanine, to form a three-base-long single-strand 5'-overhang.