Cyclin box structure of the P-TEFb subunit cyclin T1 derived from a fusion complex with EIAV Tat
Cyclin box structure of the P-TEFb subunit cyclin T1 derived from a fusion complex with EIAV Tat
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DOI：
10.1016/j.jmb.2007.04.077
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发表时间：
2007-07-27
影响因子：
5.6
通讯作者：
Geyer, Matthias
中科院分区：
文献类型：
--
作者：
Anand, Kanchan;Schulte, Antie;Geyer, Matthias
正转录延伸因子B（P-TEF B）是人类免疫缺陷病毒1型（HIV-1）生命周期中病毒基因表达的重要调节因子。其细胞周期蛋白T1亚基与病毒转录反式激活因子（达特）蛋白和反式激活应答（TAR）RNA元件形成三元复合物，从而激活细胞周期蛋白依赖性激酶9（Cdk 9），其在链延伸水平上刺激转录。我们报告的结构的周期蛋白盒域的人类细胞周期蛋白T1的分辨率为2.67埃。该结构是通过对由细胞周期蛋白T1连接到来自马传染性贫血病毒（EIAV）的反式激活蛋白达特的融合蛋白的晶体学分析获得的，该蛋白在功能和结构上与HIV-1达特相关。细胞周期蛋白T1的保守的细胞周期蛋白盒结构域表现出与生理结合伙伴如Cdk 9相互作用的结构特征。Cdk/细胞周期蛋白底物的识别位点被细胞周期蛋白T特异性插入片段部分覆盖，表明与调控因子的特异性相互作用。先前确认的。达特/ TAR识别基序（TRM）形成在细胞周期蛋白盒重复界面中部分封闭的C末端螺旋，而半胱氨酸261可接近以与达特形成分子间锌指。TRM的残基有助于带正电荷的沟，其可以直接吸引RNA分子。相反，EIAV达特蛋白从电子密度图中看起来不明确，表明它是高度无序的。功能实验证实了融合蛋白的TAR结合特性，并提示第二个细胞周期蛋白盒重复序列上的残基有助于达特刺激转录。(c)2007爱思唯尔有限公司保留所有权利。
The positive transcription elongation factor b (P-TEFb) is an essential regulator of viral gene expression during the life cycle of human immunodeficiency virus type 1 (HIV-1). Its cyclin T1 subunit forms a ternary complex with the viral transcriptional transactivator (Tat) protein and the transactivation response (TAR) RNA element thereby activating cyclin dependent kinase 9 (Cdk9), which stimulates transcription at the level of chain elongation. We report the structure of the cyclin box domain of human cyclin T1 at a resolution of 2.67 angstrom. The structure was obtained by, crystallographic analysis of a fusion protein composed of cyclin T1 linked to the transactivator protein Tat from equine infectious anemia virus (EIAV), which is functionally and structurally related to HIV-1 Tat. The conserved cyclin box domain of cyclin T1 exhibits structural features for interaction with physiological binding partners such as Cdk9. A recognition site for Cdk/Cyclin substrates is partly covered by a cyclin T-specific insert, suggesting specific interactions with regulatory factors. The previously identified. Tat/ TAR recognition motif (TRM) forms a C-terminal helix that is partly occluded in the cyclin box repeat interface, while cysteine 261 is accessible to form an intermolecular zinc finger with Tat. Residues of the TRM contribute to a positively charged groove that may directly attract RNA molecules. The EIAV Tat protein instead appeared undefined from the electron density map suggesting that it is highly disordered. Functional experiments confirmed the TAR bindhig Properties of the fusion protein and suggested residues on the second cyclin box repeat to contribute to Tat stimulated transcription. (c) 2007 Elsevier Ltd. All rights reserved.