title: S-adenosyl homocysteine and DNA ends stimulate promiscuous nuclease activities in the Type III restriction endonuclease EcoPI.
abstract: In the absence of the methyl donor S-adenosyl methionine and under certain permissive reaction conditions, EcoPI shows non-specific endonuclease activity. We show here that the cofactor analogue S-adenosyl homocysteine promotes this promiscuous DNA cleavage. Additionally, an extensive exonuclease-like processing of the DNA is also observed that can even result in digestion of non-specific DNA in trans. We suggest a model for how DNA communication events initiating from non-specific sites, and in particular free DNA ends, could produce the observed cleavage patterns.
authors.affiliation: DNA-Protein Interactions Unit, Department of Biochemistry, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, UK.
authors.forename: Luke J
authors.initials: LJ
authors.lastname: Peakman
authors.forename: Mark D
authors.initials: MD
authors.lastname: Szczelkun
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D020134:Catalytic Domain; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D053837:DNA Cleavage; D015263:Deoxyribonucleases, Type III Site-Specific / Q000737:chemistry / Q000378:metabolism*; D005090:Exodeoxyribonucleases / Q000378:metabolism*; D012435:S-Adenosylhomocysteine / Q000378:metabolism*
chemical_list: D000255:Adenosine Triphosphate; D004247:DNA; D012435:S-Adenosylhomocysteine; D005090:Exodeoxyribonucleases; C093225:DNA restriction enzyme EcoPI; D015263:Deoxyribonucleases, Type III Site-Specific