Human dihydrofolate reductase is a substrate of protein kinase CK2α
Katarzyna Skierka , Paweł Wilamowski , Monika Wielechowska , Dominik Cysewski , Elżbieta Senkara-Barwijuk , Patrycja Wińska , Maria Bretner , Joanna Cieśla
AbstractDihydrofolate reductase (DHFR) is a prominent molecular target in antitumor, antibacterial, antiprotozoan, and immunosuppressive chemotherapies, and CK2 protein kinase is an ubiquitous enzyme involved in many processes, such as tRNA and rRNA synthesis, apoptosis, cell cycle or oncogenic transformation. We show for the first time that CK2α subunit strongly interacted with and phosphorylated DHFR in vitro. Using quartz crystal microbalance with dissipation monitoring (QCM-D) we determined DHFR-CK2α binding kinetic parameters (Kd below 0.5 µM, kon = 10.31 x 104 M-1s-1 and koff = 1.40 x 10-3s-1) and calculated Gibbs free energy (-36.4 kJ/mol). In order to identify phosphorylation site(s) we used site-directed mutagenesis to obtain several DHFR mutants with predicted CK2-phosphorylable serine or threonine residues substituted with alanines. All enzyme forms were subjected to CK2α subunit catalytic activity and the results pointed to serine 168 as a phosphorylation site. Mass spectrometry analyses confirmed the presence of phosphoserine 168 and revealed additionally the presence of phosphoserine 145, although the latter phosphorylation was on a very low level.
|Journal series||Biochemical and Biophysical Research Communications, ISSN 0006-291X|
|Publication size in sheets||0.5|
|Keywords in English||protein phosphorylation, site-directed mutagenesis, dihydrofolate reductase, CK2, quartz crystal microbalance, mass spectrometry|
|ASJC Classification||; ; ;|
|Score||= 100.0, 17-08-2020, ArticleFromJournal|
|Publication indicators||= 2; = 2; : 2018 = 0.706; : 2018 = 2.705 (2) - 2018=2.55 (5)|
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