Department of Pharmacology and Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA.
Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, USA.
Nat Chem Biol. 2021 Apr;17(4):456-464. doi: 10.1038/s41589-020-00725-y. Epub 2021 Feb 1.
Cyclin-dependent kinases (CDKs) are the master regulators of the eukaryotic cell cycle. To become activated, CDKs require both regulatory phosphorylation and binding of a cognate cyclin subunit. We studied the activation process of the G1/S kinase Cdk2 in solution and developed a thermodynamic model that describes the allosteric coupling between regulatory phosphorylation, cyclin binding and inhibitor binding. The results explain why monomeric Cdk2 lacks activity despite sampling an active-like state, reveal that regulatory phosphorylation enhances allosteric coupling with the cyclin subunit and show that this coupling underlies differential recognition of Cdk2 and Cdk4 inhibitors. We identify an allosteric hub that has diverged between Cdk2 and Cdk4 and show that this hub controls the strength of allosteric coupling. The altered allosteric wiring of Cdk4 leads to compromised activity toward generic peptide substrates and comparative specialization toward its primary substrate retinoblastoma (RB).
细胞周期蛋白依赖性激酶（CDKs）是真核细胞周期的主要调节因子。为了被激活，CDKs 需要进行调节性磷酸化和与同源细胞周期蛋白亚基的结合。我们研究了 G1/S 激酶 Cdk2 在溶液中的激活过程，并开发了一个热力学模型，该模型描述了调节性磷酸化、细胞周期蛋白结合和抑制剂结合之间的变构偶联。研究结果解释了为什么单体 Cdk2 尽管采样了类似于活性的状态，但仍然缺乏活性，表明调节性磷酸化增强了与细胞周期蛋白亚基的变构偶联，并表明这种偶联是 Cdk2 和 Cdk4 抑制剂差异识别的基础。我们确定了 Cdk2 和 Cdk4 之间已经分化的变构枢纽，并且表明这个枢纽控制着变构偶联的强度。Cdk4 的变构接线已经改变，导致其对通用肽底物的活性降低，并且对其主要底物视网膜母细胞瘤（RB）的特异性增强。
