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Casein kinase 1δ activates human recombinant deoxycytidine kinase by Ser-74 phosphorylation, but is not involved in thein vivoregulation of its activity

Authors
Journal
Archives of Biochemistry and Biophysics
0003-9861
Publisher
Elsevier
Publication Date
Volume
502
Issue
1
Identifiers
DOI: 10.1016/j.abb.2010.07.009
Keywords
  • Deoxycytidine Kinase
  • Ser-74 Phosphorylation
  • Casein Kinase 1δ
  • Post-Translational Modification
  • Nucleoside Analogue
  • B-Cll Cells
Disciplines
  • Biology

Abstract

Abstract Deoxycytidine kinase (dCK) is a key enzyme in the salvage of deoxynucleosides and in the activation of several anticancer and antiviral nucleoside analogues. We recently showed that dCK was activated in vivo by phosphorylation of Ser-74. However, the protein kinase responsible was not identified. Ser-74 is located downstream a Glu-rich region, presenting similarity with the consensus phosphorylation motif of casein kinase 1 (CKI), and particularly of CKI δ. We showed that recombinant CKI δ phosphorylated several residues of bacterially overexpressed dCK: Ser-74, but also Ser-11, Ser-15, and Thr-72. Phosphorylation of dCK by CKI δ correlated with increased activity reaching at least 4-fold. Site-directed mutagenesis demonstrated that only Ser-74 phosphorylation was involved in dCK activation by CKI δ, strengthening the key role of this residue in the control of dCK activity. However, neither CKI δ inhibitors nor CKI δ siRNA-mediated knock-down modified Ser-74 phosphorylation or dCK activity in cultured cells. Moreover, these approaches did not prevent dCK activation induced by treatments enhancing Ser-74 phosphorylation. Taken together, the data preclude a role of CKI δ in the regulation of dCK activity in vivo. Nevertheless, phosphorylation of dCK by CKI δ could be a useful tool for elucidating the influence of Ser-74 phosphorylation on the structure–activity relationships in the enzyme.

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