[Two site-specific endonucleases from the thermophilic strain Bacillus species LU11].

Upon screening of natural strains of thermophilic bacteria, a strain has been found which contains two restriction endonucleases. One of those, BspLU11II, is an isoschizomer of XbaI, while the other one, BspLU11I, recognizes the new palindromic sequence 5'-A decreases CATGT-3' and cleaves it as indicated by the arrow. Functionally pure enzymes were obtained by stepwise chromatography with blueagarose, hydroxyapatite and heparin-Sepharose. The restriction endonuclease BspLU11I produces sticky ends identical to those produced by the restriction endonuclease NcoI; hence a combination of BspLU11I and NcoI can be used for enzymatic selection of recombinant DNA. The recognition sequence of BspLU11I contains the ATG codon and can be used to construct expression vectors for chemically synthesized genes.