Restriction enzyme BstZ17I is sensitive to cytosine methylation

The cleavage patterns of a subset of restriction enzymes are blocked or imp aired when a methylated CpG is overlapped with either the 5' or 3' end of t he canonical restriction site. BstZ17I restriction endonuclease is a blunt- end cutter. which recognises the hexanucleotide sequence GTA(down arrow)TAC . In this report, I show that the BstZ17I restriction enzyme is sensitive t o cytosine methylation. Using both in vitro-methylated episomal plasmids an d lambda DNA, I demonstrate that the BstZ17I restriction enzyme is sensitiv e to cytosine methylation that occurs 3' and/or 5' of the canonical recogni tion sequence. (C) 2001 Published by Elsevier Science B.V. on behalf of the Federation of European Microbiological Societies.