The structure of P-TEFb (CDK9/cyclin T1), its complex with flavopiridol and regulation by phosphorylation
The structure of P-TEFb (CDK9/cyclin T1), its complex with flavopiridol and regulation by phosphorylation
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DOI：
10.1038/emboj.2008.121
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发表时间：
2008-07-09
期刊：
影响因子：
11.4
通讯作者：
Johnson, Louise N.
中科院分区：
文献类型：
--
作者：
Baumli, Sonja;Lolli, Graziano;Johnson, Louise N.
正转录延伸因子B（P-TEF B）（CDK 9/细胞周期蛋白T（CycT））通过延伸阻遏物和RNA聚合酶II的磷酸化促进mRNA转录延伸。为了了解转录CDK的调节其同源细胞周期蛋白，我们已经确定了CDK 9/CycT 1和游离细胞周期蛋白T2的结构。CDK 9/CycT 1和细胞周期CDK CDK 2/CycA之间存在明显差异，表现为CycT 1相对于CDK的相对旋转261，首次显示了CDK细胞周期蛋白相互作用的可塑性。CDK 9/CycT 1界面相对稀疏，但保留了一些核心CDK-cyclin相互作用。CycT 1的C-末端螺旋显示的灵活性，可能是重要的相互作用，该地区与HIV达特和HEXIM。Flavopiridol是一种处于II期临床试验中的抗癌药物，它与CDK 9的ATP位点结合，诱导意外的结构变化，从而掩盖抑制剂。CDK 9的活性和调节蛋白的识别由自磷酸化控制。我们发现，CDK 9/CycT 1自磷酸化的Thr 186的激活段和三个C-末端磷酸化位点。所有位点上的自磷酸化均以顺式发生。
The positive transcription elongation factor b (P-TEFb) (CDK9/cyclin T (CycT)) promotes mRNA transcriptional elongation through phosphorylation of elongation repressors and RNA polymerase II. To understand the regulation of a transcriptional CDK by its cognate cyclin, we have determined the structures of the CDK9/CycT1 and free cyclin T2. There are distinct differences between CDK9/CycT1 and the cell cycle CDK CDK2/CycA manifested by a relative rotation of 261 of CycT1 with respect to the CDK, showing for the first time plasticity in CDK cyclin interactions. The CDK9/CycT1 interface is relatively sparse but retains some core CDK-cyclin interactions. The CycT1 C-terminal helix shows flexibility that may be important for the interaction of this region with HIV TAT and HEXIM. Flavopiridol, an anticancer drug in phase II clinical trials, binds to the ATP site of CDK9 inducing unanticipated structural changes that bury the inhibitor. CDK9 activity and recognition of regulatory proteins are governed by autophosphorylation. We show that CDK9/CycT1 autophosphorylates on Thr186 in the activation segment and three C-terminal phosphorylation sites. Autophosphorylation on all sites occurs in cis.