Bael, another unusual Bcgl-like restriction endonuclease

Bcgl and Bcgl-like restriction endonucleases have a very distinct characteristic which causes them to differ from the other classified restriction enzymes; they all cleave double-stranded DNA specifically on both sides of the recognition sequence to excise a short DNA fragment including the recognition sites. Here we report a new Bcgl-like restriction endonuclease. Bael, isolated from Bacillus sphaericus. Like Bcgl, Bael also cleaves double-stranded DNA on both strands upstream and downstream of its recognition sequence (10/15)ACNNNNGTAYC(12/7). There are two dominant polypeptides in the final preparation of Bael with molecular masses of similar to 80 and 55 kDa. Both are slightly larger than the two Bcgl subunits. Bael requires both Mg2+ and AdoMet to cleave DNA. Accompanying bilateral cleavage activity, the heteromeric Bael also has an N6-adenine methyltransferase activity which modifies the symmetrically located adenines within its recognition sequence.