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Structural and kinetic mechanism of CDK2 inhibiton by Y15 phosphorylation
Author(s) -
Lindert Lisa M,
Welburn Julie,
Tucker Julie,
Johnson Tim,
Morgan Marc,
Noble Martin
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a461-c
Subject(s) - mechanism (biology) , chemistry , phosphorylation , kinetic energy , biophysics , biochemistry , physics , biology , quantum mechanics
Cyclin‐dependent kinases (CDKs) are inhibited by phosphorylation at Y15 in response to activation of DNA damage checkpoints and as a key regulatory point in normal control of the eukaryotic cell cycle. The structure of a Tyr15pThr160pCDK2/cyclinA/AMPPNP complex reveals that Tyr15 phosphorylation blocks peptide substrate binding but does not inhibit ATP binding. The phosphate group is exposed to solvent and is engaged in a hydrogen‐bonded network with water molecules. Kinetic studies show that the Tyr15Thr160 phosphorylated complex binds ATP with similar affinity to the singly phosphorylated, fully active Thr160P enzyme and retains its ability to transfer phosphate to water (ATPase activity). This ATPase rate is similar to that of the dually phosphorylated complex. In contrast, we observe a dramatically decreased affinity and activity towards the peptide substrate (PKTPKKAKKL). Our structural and kinetic results indicate that the basis for CDK inhibition through Y15 phosphorylation is to block the enzyme’s kinase activity with little effect on its ATPase activity.