title: A mutation in the Mod subunit of EcoP15I restriction enzyme converts the DNA methyltransferase to a site-specific endonuclease.
abstract: A closer inspection of the amino acid sequence of EcoP15I DNA methyltransferase revealed a region of similarity to the PDXn(D/E)XK catalytic site of type II restriction endonucleases, except for methionine in EcoP15I DNA methyltransferase instead of proline. Substitution of methionine at position 357 by proline converts EcoP15I DNA methyltransferase to a site-specific endonuclease. EcoP15I-M357P DNA methyltransferase specifically binds to the recognition sequence 5'-CAGCAG-3' and cleaves DNA asymmetrically EcoP151-M357P.DNA methyltransferase specifically binds to the recognition sequence 5'-CAGCAG-3' and cleaves DNA asymmetrically, 5'-CAGCAG(N)(10)-3', as indicated by the arrows, in presence of magnesium ions.
authors.affiliation: Department of Biochemistry, Indian Institute of Science, Bangalore 560 012, India.
authors.forename: Pradeep
authors.initials: P
authors.lastname: Bist
authors.forename: Urulangodi Kunhiraman
authors.initials: UK
authors.lastname: Madhusoodanan
authors.forename: Desirazu N
authors.initials: DN
authors.lastname: Rao
mesh_terms: D000595:Amino Acid Sequence; D004252:DNA Mutational Analysis; D004269:DNA, Bacterial / Q000235:genetics; D004278:DNA, Superhelical / Q000235:genetics; D015263:Deoxyribonucleases, Type III Site-Specific / Q000737:chemistry / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding / Q000235:genetics; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific) / Q000096:biosynthesis / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D004269:DNA, Bacterial; D004278:DNA, Superhelical; D029968:Escherichia coli Proteins; D021122:Protein Subunits; C089712:DNA modification methylase EcoP15I; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific); C023451:endodeoxyribonuclease EcoP15I; D015263:Deoxyribonucleases, Type III Site-Specific; D008274:Magnesium