title: Self-methylation of BspRI DNA-methyltransferase.
abstract: The DNA (cytosine-5)-methyltransferase (m5C-MTase) M.BspRI is able to accept the methyl group from the methyl donor S-adenosyl-L-methionine (AdoMet) in the absence of DNA. Transfer of the methyl group to the enzyme is a slow reaction relative to DNA methylation. Self-methylation is dependent on the native conformation of the enzyme and is inhibited by S-adenosyl-L-homocysteine, DNA and sulfhydryl reagents. Amino acid sequencing of proteolytic peptides obtained from M.BspRI, which had been methylated with [methyl-3H]AdoMet, and thin layer chromatography of the modified amino acid identified two cysteines, Cys156 and Cys181 that bind the methyl group in form of S-methylcysteine. One of the acceptor residues, Cys156 is the highly conserved cysteine which plays the role of the catalytic nucleophile of m5C-MTases.
authors.affiliation: Institute of Biochemistry, Hungarian Academy of Sciences, Szeged.
authors.forename: L
authors.initials: L
authors.lastname: Szilák
authors.forename: C
authors.initials: C
authors.lastname: Finta
authors.forename: A
authors.initials: A
authors.lastname: Patthy
authors.forename: P
authors.initials: P
authors.lastname: Venetianer
authors.forename: A
authors.initials: A
authors.lastname: Kiss
mesh_terms: D000595:Amino Acid Sequence; D001667:Binding, Competitive; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D003545:Cysteine / Q000378:metabolism; D004247:DNA / Q000494:pharmacology; D015257:DNA-Cytosine Methylases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology*; D008745:Methylation; D008969:Molecular Sequence Data; D011487:Protein Conformation; D012435:S-Adenosylhomocysteine / Q000494:pharmacology; D012436:S-Adenosylmethionine / Q000378:metabolism; D013439:Sulfhydryl Reagents / Q000494:pharmacology; D014316:Tritium
chemical_list: D013439:Sulfhydryl Reagents; D014316:Tritium; D012436:S-Adenosylmethionine; D004247:DNA; D012435:S-Adenosylhomocysteine; D015257:DNA-Cytosine Methylases; C027823:Cytosine 5-methyltransferase; D003545:Cysteine