Site-specific nickase from Bacillus species strain D6

Three site-specific endonucleases were found in thermophilic strain Bacillu s species D6. One of them, BspD6II, is an isoschizomer of Eco57I. The secon d, BspD6III, is present in the strain in very small amount; therefore, it h as not been characterized. This paper is devoted to the third, BspD6I, whic h recognizes pentanucleotide site 5'-GAGTC-3' and cleaves only one DNA stra nd at a distance of 4 nucleotides from the site in the 3'-direction in the chain with the GAGTC sequence, i.e., it behaves as a site-specific nickase. Nickase N.BspD6I cleaves one DNA strand only in double-stranded DNA and do es not cleave single-stranded DNA. Site-specific methylase SscL1I (an isohy pectomer of M.HinfI) that methylates adenine in the sequence 5'-GANTC-3' pr events DNA hydrolysis by nickase BspD6I.