title: Binding of polyamines to an autonomous domain of the regulatory subunit of protein kinase CK2 induces a conformational change in the holoenzyme. A proposed role for the kinase stimulation.
abstract: The means by which the cell regulates protein kinase CK2 remain obscure. However, natural polyamines, cellular compounds required for cell proliferation, have been reported to strongly stimulate CK2-mediated phosphorylation of a number of substrates. Using spermine analogs, we have shown that polyamines directly interact with the CK2 beta subunit, and the chemical features of the highly acidic binding site (Asp51-Tyr80) have been determined. In the present study, we show that the isolated beta subunit region extending from residue Asp51 to Pro110 exhibits a specific and efficient polyamine binding activity similar to that of the entire beta subunit. Moreover, the replacement of Glu60, Glu61, and Glu63 of the beta subunit by 3 alanine residues leads to a loss of the spermine-induced stimulation of CK2 activity which correlates with a decrease in spermine binding affinity. Thermal stability studies indicate that the binding of spermine induces a 4 degrees C decrease of the Tm value for the holoenzyme. This was confirmed by circular dichroism analyses, which show that the 6 degrees C negative shift of the CK2 Tm value provoked by spermine binding, reflects a conformational change in the kinase. Together, these observations strongly suggest that this newly defined polyamine-binding domain is involved in the intrasteric regulation of CK2 activity.
authors.affiliation: Laboratoire de Biochimie des Régulations Cellulaires Endocrines, Département de Biologie Moléculaire et Structurale, INSERM Unité 244, CEA Grenoble, 17 rue des Martyrs, F-38054 Grenoble Cedex 9, France.
authors.forename: D
authors.initials: D
authors.lastname: Leroy
authors.forename: J K
authors.initials: JK
authors.lastname: Heriché
authors.forename: O
authors.initials: O
authors.lastname: Filhol
authors.forename: E M
authors.initials: EM
authors.lastname: Chambaz
authors.forename: C
authors.initials: C
authors.lastname: Cochet
mesh_terms: D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D047390:Casein Kinase II; D003067:Coenzymes / Q000737:chemistry*; D004795:Enzyme Stability; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000378:metabolism*; D013096:Spermine / Q000378:metabolism*; D013329:Structure-Activity Relationship
chemical_list: D003067:Coenzymes; D013096:Spermine; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases