[A new site specific endonuclease-methylase from a thermophilic strain of Bacillus species LU11]

A new site-specific endonuclease BspLU11III was purified to homogeneity from a thermophilic strain Bacillus species LU11. BspLU11III recognizes the 5'-GGGAC-3' sequence on the double-stranded DNA and cleaves the 10/14 and 11/15 nucleotides in different strands away from the recognition site. The enzyme exists in solution as a monomer with a molecular mass of about 93 kDa. When incubated with S-adenosyl-L-methionine, BspLU11III displays a DNA-methyltransferase activity. The adenine residue is methylated inside the recognition site 5'-GGGAC-3' in the only strand. The restriction activity does not change in the presence of ATP but is stimulated by 80 microM S-adenosyl-L-methionine (4-fold). Magnesium cations are needed for the restriction activity. Sodium chloride stimulates the "star" activity of BspLU11III. According to its properties, BspLU11III can be classified as a type IV endonuclease.