title: Endonuclease from Acholeplasma laidlawii strain JA1 associated with in vivo restriction of DNA containing 5-methylcytosine.
abstract: Transfection of Acholeplasma laidlawii strain JA1 with viral DNAs that have been sequence-specifically methylated in vitro has led us to previously postulate that JA1 cells contain an enzyme which cleaves only DNA containing 5-methylcytosine, regardless of the nucleotide sequence containing that base. In this paper we show that an endonuclease activity is present in extracts from JA1 cells but not in extracts from a restriction-deficient variant of JA1. The partially purified enzyme cleaves not only DNA containing 5-methylcytosine, but also DNA containing no methylated bases. We discuss why this endonuclease activity may not have the same in vitro specificity as would be expected from in vivo experiments.
authors.affiliation: Department of Microbiology and Immunology, University of Rochester Medical Center, New York.
authors.forename: T L
authors.initials: TL
authors.lastname: Sladek
authors.forename: J
authors.initials: J
authors.lastname: Maniloff
mesh_terms: D044503:5-Methylcytosine; D000128:Acholeplasma laidlawii / Q000201:enzymology*; D001426:Bacterial Proteins / Q000302:isolation & purification* / Q000378:metabolism; D003596:Cytosine / Q000031:analogs & derivatives* / Q000032:analysis; D004247:DNA / Q000378:metabolism; D004262:DNA Restriction Enzymes / Q000302:isolation & purification* / Q000378:metabolism; D004269:DNA, Bacterial / Q000378:metabolism*; D004270:DNA, Circular / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004270:DNA, Circular; D044503:5-Methylcytosine; D003596:Cytosine; D004247:DNA; D004262:DNA Restriction Enzymes