Open AccessPhosphorylation of DNA topoisomerase II by casein kinase II: modulation of eukaryotic topoisomerase II activity in vitro.
Author(s) -
Pat Ackerman,
Claiborne V.C. Glover,
Neil Osheroff
Publication year - 1985
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.82.10.3164
Subject(s) - topoisomerase , autophosphorylation , casein kinase 1 , biochemistry , phosphorylation , kinase , casein kinase 2, alpha 1 , casein kinase 2 , microbiology and biotechnology , phosphatase , biology , serine , enzyme , dna , protein kinase a , chemistry , cyclin dependent kinase 2
The phosphorylation of Drosophila melanogaster DNA topoisomerase II by purified casein kinase II was characterized in vitro. Under the conditions used, the kinase incorporated a maximum of 2-3 molecules of phosphate per homodimer of topoisomerase II. No autophosphorylation of the topoisomerase was observed. The only amino acid residue modified by casein kinase II was serine. Apparent Km and Vmax values for the phosphorylation reaction were 0.4 microM topoisomerase II and 3.3 mumol of phosphate incorporated per min per mg of kinase, respectively. Phosphorylation stimulated the DNA relaxation activity of topoisomerase II by 3-fold over that of the dephosphorylated enzyme, and the effects of modification could be reversed by treatment with alkaline phosphatase. Therefore, this study demonstrates that post-translational enzymatic modifications can be used to modulate the interaction between topoisomerase II and DNA.