Phosphorylation of Calmodulin Fragments by Protein Kinase CK2. Mechanistic Aspects and Structural Consequences
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- 作者：Giorgio Arrigoni ; Oriano Marin ; Mario A. Pagano ; Luca Settimo ; Bruno Paolin ; Flavio Meggio ; and Lorenzo A. Pinna
- 刊名：Biochemistry
- 出版年：2004
- 出版时间：October 12, 2004
- 年：2004
- 卷：43
- 期：40
- 页码：12788 - 12798
- 全文大小：243K
- 年卷期：v.43,no.40(October 12, 2004)
- ISSN：1520-4995
文摘
Calmodulin is phosphorylated in vivo and in vitro by protein kinase CK2 in a manner that isunique among CK2 substrates for being inhibited by the regulatory 
-subunit of the kinase and dramaticallyenhanced by polybasic peptides. Using synthetic fragments of calmodulin variably encompassing the CK2phosphorylation sites here we show that individual phosphorylation of Thr79, Ser81, Ser101, and Thr117is critically influenced by the size and composition of the peptides and that the C-terminal domain ofcalmodulin is implicated both in down-regulation of calmodulin phosphorylation by the -subunit and inits abnormal responsiveness to polylysine. A far-Western blot analysis discloses polylysine-dependentinteraction between calmodulin and the N-terminal domain of the -subunit. We also show thatphosphorylation of Ser81 hampers subsequent phosphorylation of Thr79 and by itself promotes the unfoldingof the central helix, whose flexibility is instrumental to the interaction with calmodulin-dependent enzymes.Collectively taken, our data are consistent with a multifaceted regulation of calmodulin phosphorylationthrough the concerted action of distinct CaM domains, the catalytic and regulatory subunits of CK2, andpolycationic effectors mimicking in vivo the effect of polylysine.
-subunit of the kinase and dramaticallyenhanced by polybasic peptides. Using synthetic fragments of calmodulin variably encompassing the CK2phosphorylation sites here we show that individual phosphorylation of Thr79, Ser81, Ser101, and Thr117is critically influenced by the size and composition of the peptides and that the C-terminal domain ofcalmodulin is implicated both in down-regulation of calmodulin phosphorylation by the -subunit and inits abnormal responsiveness to polylysine. A far-Western blot analysis discloses polylysine-dependentinteraction between calmodulin and the N-terminal domain of the -subunit. We also show thatphosphorylation of Ser81 hampers subsequent phosphorylation of Thr79 and by itself promotes the unfoldingof the central helix, whose flexibility is instrumental to the interaction with calmodulin-dependent enzymes.Collectively taken, our data are consistent with a multifaceted regulation of calmodulin phosphorylationthrough the concerted action of distinct CaM domains, the catalytic and regulatory subunits of CK2, andpolycationic effectors mimicking in vivo the effect of polylysine.