title: Activation of mammalian DNA ligase I through phosphorylation by casein kinase II.
abstract: Mammalian DNA ligase I has been shown to be a phosphoprotein. Dephosphorylation of purified DNA ligase I causes inactivation, an effect dependent on the presence of the N-terminal region of the protein. Expression of full-length human DNA ligase I in Escherichia coli yielded soluble but catalytically inactive enzyme whereas an N-terminally truncated form expressed activity. Incubation of the full-length preparation from E. coli with purified casein kinase II (CKII) resulted in phosphorylation of the N-terminal region and was accompanied by activation of the DNA ligase. Of a variety of purified protein kinases tested, only CKII stimulated the activity of calf thymus DNA ligase I. Tryptic phosphopeptide analysis of DNA ligase I revealed that CKII specifically phosphorylated a major peptide also apparently phosphorylated in cells, implying that CKII is a protein kinase acting on DNA ligase I in the cell nucleus. These data suggest that DNA ligase I is negatively regulated by its N-terminal region and that this inhibition can be relieved by post-translational modification.
authors.affiliation: Imperial Cancer Research Fund, Clare Hall Laboratories, South Mimms, Herts, UK.
authors.forename: C
authors.initials: C
authors.lastname: Prigent
authors.forename: D D
authors.initials: DD
authors.lastname: Lasko
authors.forename: K
authors.initials: K
authors.lastname: Kodama
authors.forename: J R
authors.initials: JR
authors.lastname: Woodgett
authors.forename: T
authors.initials: T
authors.lastname: Lindahl
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001665:Binding Sites; D047390:Casein Kinase II; D002417:Cattle; D002460:Cell Line; D003001:Cloning, Molecular; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D004789:Enzyme Activation; D004926:Escherichia coli / Q000235:genetics; D006801:Humans; D008961:Models, Structural; D009132:Muscles / Q000201:enzymology; D010748:Phosphopeptides / Q000302:isolation & purification; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000302:isolation & purification / Q000378:metabolism*; D011817:Rabbits; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D013950:Thymus Gland / Q000201:enzymology*
chemical_list: D000596:Amino Acids; C000607892:LIG1 protein, human; D010748:Phosphopeptides; D011994:Recombinant Proteins; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases; D011088:DNA Ligases; D000072481:DNA Ligase ATP