title: The EcoA restriction and modification system of Escherichia coli 15T-: enzyme structure and DNA recognition sequence.
abstract: The EcoA restriction enzyme from Escherichia coli 15T- has been isolated. It proves to be an unusual enzyme, clearly related functionally to the classical type I restriction enzymes. The basic enzyme is a two subunit modification methylase. Another protein species can be purified which by itself has no enzymatic activities but which converts the modification methylase to an ATP and S-adenosylmethionine-dependent restriction endonuclease. The DNA recognition sequence of EcoA has an overall structure that is very similar to previously determined type I sequences. It is: 5'-GAGNNNNNNNGTCA-3' 3'-CTCNNNNNNNCAGT-5' where N can be any nucleotide. Modification methylates the adenosyl residue in the specific trinucleotide and the adenosyl residue in the lower strand of the specific tetranucleotide.
mesh_terms: D001483:Base Sequence; D004262:DNA Restriction Enzymes / Q000302:isolation & purification / Q000378:metabolism; D015253:Deoxyribonucleases, Type I Site-Specific; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D008745:Methylation; D008970:Molecular Weight; D013379:Substrate Specificity
chemical_list: D004262:DNA Restriction Enzymes; C040446:endodeoxyribonuclease EcoAI; D015253:Deoxyribonucleases, Type I Site-Specific