title: Single-strand and double-strand cleavage at half-modified and fully modified recognition sites for the restriction nucleases Sau3a and Taqi.
abstract: The influence of cytosine methylation on the cleavage of DNA by the restriction nucleases Sau3A and TaqI has been investigated. Bovine satellite DNA fragments containing a GATCGA sequence, i.e. a Sau3A site overlapping with a TaqI site have been used in this study. The methylation of these fragments has been determined by sequence analysis. It has been found that a TaqI site (TCGA) methylated at cytosine in both DNA strands is still sensitive to double-strand cleavage. A Sau3A site (GATC), however, is rendered resistant to double-strand cleavage by methylation of a single cytosine. Fragments containing the "half-modified" Sau3A site are nicked in the unmethylated DNA strand. It has been shown by sequence analysis of nicked DNA that the single-strand break occurs at the same position which is cleaved in unmodified DNA.
mesh_terms: D000818:Animals; D001483:Base Sequence; D002417:Cattle; D003001:Cloning, Molecular; D003596:Cytosine / Q000378:metabolism; D004262:DNA Restriction Enzymes / Q000378:metabolism*; D004276:DNA, Satellite / Q000032:analysis / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D008745:Methylation; D013211:Staphylococcus aureus / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D004276:DNA, Satellite; D003596:Cytosine; D004262:DNA Restriction Enzymes