Polyamine-activated protein kinase reaction from nuclei and nucleoli of Physarum polycephalum which phosphorylates a unique Mr 70 000 nonhistone protein.
Methods are described for the detection and purification of a protein kinase from nuclei and nucleoli of Physarum polycephalum which catalyzed transfer of phosphate from [gamma-32P]ATP to a unique nonhistone protein of Mr 70 000 in a reaction that was polyamine dependent. Enzymatic phosphorylation of the nonhistone protein by the purified protein kinase was stimulated greatly, at times more than 60-fold, by the polyamines spermidine and spermine. This unique polyamine-dependent reaction was localized on the rDNA minichromosome of the nucleolus. The polyamine-dependent protein kinase, which was first partially purified with the acidic nonhistone protein fraction from isolated nucleoli, was resolved from at least six other protein kinases by phosphocellulose chromatography into a catalytic component of Mr 26 000 and a complex comprised of the catalytic component associated with a phosphate acceptor protein of Mr 70 000. The complex also catalyzed polyamine-dependent phosphorylation of the endogenous Mr 70 000 component. The resolved catalytic component catalyzed polyamine-dependent phosphorylation of a dephosphorylated Mr 70 000 nonhistone protein that had been independently isolated from nucleoli and previously demonstrated to have properties concordant with a specific regulatory role in rRNA gene transcription [Keuhn, G. D., Affolter, H. U., Atmar, V. J., Seebeck, T., Gubler, U., & Braun, R. (1979) Proc. Natl. Acad. Sci. U.S.A. 76, 2541-2545]. These studies indicate one way that the polyamines may regulate rRNA gene transcription through the mediation of a highly specific nonhistone protein kinase.
D002466:Cell Nucleolus / Q000201:enzymology*; D002467:Cell Nucleus / Q000201:enzymology*; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D004789:Enzyme Activation; D007700:Kinetics; D008970:Molecular Weight; D010766:Phosphorylation; D010804:Physarum / Q000201:enzymology*; D011073:Polyamines / Q000494:pharmacology*; D011494:Protein Kinases / Q000378:metabolism*; D013095:Spermidine / Q000494:pharmacology; D013096:Spermine / Q000494:pharmacology
D002868:Chromosomal Proteins, Non-Histone; D011073:Polyamines; D013096:Spermine; D011494:Protein Kinases; D013095:Spermidine