AsnI: a novel class II restriction endonuclease from Arthrobacter sp., strain N-CM, recognizing 5'-AT/TAAT-3'.

A new class II restriction endonuclease, AsnI, with a novel sequence specificity was isolated from the Gram-positive eubacterium Arthrobacter species, strain N-CM. AsnI recognizes the unambiguously defined palindromic hexanucleotide (Formula: see text) consisting of A- and T-residues. The novel enzyme in the presence of Mg2+ cleaves specifically both strands as indicated by the arrows. The staggered cuts generate 5'-protruding ends with single-stranded 5'-TA-3' dinucleotide extensions. The novel enzyme may be a useful tool for cloning experiments by complementation of the few enzymes such as PstI and PvuI cutting only once in the Ampr-gene of plasmids pBR322 and pBR328.