title: Functional domains and methyl acceptor sites of the Escherichia coli ada protein.
abstract: The ada gene of Escherichia coli encodes a 39-kDa protein which serves both as a transcriptional activator of the adaptive response to alkylating agents and as a DNA repair enzyme demethylating O6-methyl-guanine and phosphotriester residues. Here, the isolated Ada protein was found to be readily cleaved into two fragments of similar size by treatment with trypsin, chymotrypsin, subtilisin, or V8 protease. The fragments retained their respective methyltransferase activities. The Ada protein is, therefore, comprised of two stable active domains united by a central hinge region of about 10 amino acids. Post-translational modification of the Ada protein by methylation of a specific cysteine residue in the NH2-terminal domain is known to convert it to an efficient transcriptional activator. This residue has now been identified as Cys-69.
authors.affiliation: Imperial Cancer Research Fund, Clare Hall Laboratories, South Mimms, Herts, London, United Kingdom.
authors.forename: B
authors.initials: B
authors.lastname: Sedgwick
authors.forename: P
authors.initials: P
authors.lastname: Robins
authors.forename: N
authors.initials: N
authors.lastname: Totty
authors.forename: T
authors.initials: T
authors.lastname: Lindahl
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D002851:Chromatography, High Pressure Liquid; D002918:Chymotrypsin / Q000378:metabolism; D004260:DNA Repair; D029968:Escherichia coli Proteins; D008745:Methylation; D019853:O(6)-Methylguanine-DNA Methyltransferase; D010449:Peptide Mapping; D012697:Serine Endopeptidases / Q000378:metabolism; D014157:Transcription Factors; D014357:Trypsin / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D014157:Transcription Factors; C045675:Ada protein, E coli; D019853:O(6)-Methylguanine-DNA Methyltransferase; D012697:Serine Endopeptidases; D002918:Chymotrypsin; C028344:glutamyl endopeptidase; D014357:Trypsin