Molecular assembly of the period-cryptochrome circadian transcriptional repressor complex.
Molecular assembly of the period-cryptochrome circadian transcriptional repressor complex.
复制标题
DOI：
10.7554/elife.03674
复制
发表时间：
2014-08-15
期刊：
影响因子：
7.7
通讯作者：
Zheng N
中科院分区：
文献类型：
--
作者：
Nangle SN;Rosensweig C;Koike N;Tei H;Takahashi JS;Green CB;Zheng N
哺乳动物的生物钟是由转录-翻译反馈回路驱动的，该回路产生稳健的24小时节律。时钟的正确振荡取决于周期蛋白和隐花色素蛋白的复合物形成和周期性周转，它们共同抑制它们自己的转录激活因子复合物CLOCK-BMAL 1。我们以2.8 μ m的分辨率测定了PER 2与P450 2复合物中的P450结合结构域（CBD）的晶体结构。PER 2-CBD采用高度延伸的构象，以弯曲的结合模式拥抱PER 2。它的N-末端塞入CRY中，邻近对CLOCK-BMAL 1结合至关重要的大口袋，而它的C-末端半侧接于CRY 2 C-末端螺旋，并在空间上阻碍FBXL 3泛素连接酶对CRY 2的识别。出乎意料的是，一个严格保守的分子间锌指，其完整性是重要的时钟节奏，进一步稳定的复杂。我们的结构引导的分析表明，这些散布的PRES相互作用的区域代表多个功能模块的PER在PRES结合界面。http://dx.doi.org/10.7554/eLife.03674.001自从地球上出现最简单的有机体以来，生命的节奏就与太阳的升起和落下同步。即使是最基本的生命形式也有内部时钟，帮助他们维持日常生活并适应季节的变化。在动物中，这些内部时钟调节着诸如唤醒动物的激素释放和进行日常生活活动所必需的基因表达等过程。之后，生物钟会触发导致困倦的激素的释放，以及在休息时活跃的基因的表达。在哺乳动物中，这些内部昼夜节律是由四种关键蛋白质控制的反馈回路维持的。其中两种蛋白质--CLOCK和BMAL 1--协同工作，开始一个称为转录的过程，即DNA片段被用作模板，复制制造蛋白质所需的信息。两种激活蛋白CLOCK和BMAL 1识别由生物钟控制的基因所在的DNA部分，并选择性地打开这些基因的表达。另外两个关键的昼夜节律蛋白周期和隐花色素的表达是由CLOCK和BMAL 1启动的。随着周期蛋白和隐花色素蛋白的积累，它们开始抑制CLOCK和BMAL 1的活性，有助于降低昼夜节律基因随着时间推移而转录的速率。Nangle等人提供了关于Period和Cryptochrome蛋白如何相互作用的新见解，使用X射线晶体学揭示了两种蛋白质之间键合的分子水平细节。时期延伸，因为它'拥抱' Cryptochrome。然后，周期蛋白的一端进入一个大口袋旁边的隐花色素结构的一部分。这个口袋是隐花色素蛋白与CLOCK和BMAL 1结合的地方，这表明周期可以影响这种结合是否发生。Period蛋白的另一端覆盖Cryptochrome蛋白的一端。这样，酶就不能结合在那里，因此不能分解隐花色素。Nangle等人还发现，含有锌离子的指状突起起到了扣钩的作用，加强了Period和Cryptochrome之间的结合。这些发现有助于证明周期蛋白如何作为计时器，调节隐花色素可以在多长时间内降低CLOCK和BMAL 1的活性。更深入地了解四种时钟蛋白质之间的分子编排，有望开发药物来治疗与现代生活方式相关的睡眠障碍和生物钟中断。DOI：http://dx.doi.org/10.7554/eLife.03674.002网站
The mammalian circadian clock is driven by a transcriptional–translational feedback loop, which produces robust 24-hr rhythms. Proper oscillation of the clock depends on the complex formation and periodic turnover of the Period and Cryptochrome proteins, which together inhibit their own transcriptional activator complex, CLOCK-BMAL1. We determined the crystal structure of the CRY-binding domain (CBD) of PER2 in complex with CRY2 at 2.8 Å resolution. PER2-CBD adopts a highly extended conformation, embracing CRY2 with a sinuous binding mode. Its N-terminal end tucks into CRY adjacent to a large pocket critical for CLOCK-BMAL1 binding, while its C-terminal half flanks the CRY2 C-terminal helix and sterically hinders the recognition of CRY2 by the FBXL3 ubiquitin ligase. Unexpectedly, a strictly conserved intermolecular zinc finger, whose integrity is important for clock rhythmicity, further stabilizes the complex. Our structure-guided analyses show that these interspersed CRY-interacting regions represent multiple functional modules of PERs at the CRY-binding interface. DOI: http://dx.doi.org/10.7554/eLife.03674.001 Since the very simplest organisms emerged on earth, the rhythms of life have been synchronized with the rising and setting of the sun. Even the most basic life forms have internal clocks that help them to maintain daily routines and adapt to shifting seasons. In animals, these internal clocks regulate processes such as the release of hormones that wake an animal up and the expression of genes necessary to carry out the activities of daily life. Later on, the clocks then trigger the release of hormones that cause drowsiness and the expression of the genes that are active during rest. In mammals, these internal circadian rhythms are maintained by a feedback loop governed by four key proteins. Two of these proteins—CLOCK and BMAL1—work together to begin a process called transcription, whereby sections of DNA are used as a template to copy the information needed to make a protein. The two activating proteins CLOCK and BMAL1 recognize the sections of DNA where the genes that are controlled by the circadian clock are located and selectively turn on the expression of those genes. Expression of the two other key circadian proteins—Period and Cryptochrome—is switched on by CLOCK and BMAL1. As Period and Cryptochrome proteins accumulate, they begin to inhibit the activity of CLOCK and BMAL1, helping to reduce the rate at which the circadian genes are transcribed as the day progresses. Nangle et al. provide new insights into how the Period and Cryptochrome proteins interact with each other, using X-ray crystallography to reveal the molecular level details of the bond between the two proteins. Period stretches out as it ‘embraces’ Cryptochrome. One end of the Period protein then tucks into part of the Cryptochrome structure that is next to a large pocket. This pocket is where the Cryptochrome protein binds to CLOCK and BMAL1, suggesting that Period can influence whether this binding occurs. The other end of the Period protein covers one end of the Cryptochrome protein. By doing so, enzymes cannot bind there, and so cannot break down Cryptochrome. Nangle et al. also discovered that a finger-like projection that includes a zinc ion acts as a clasp, strengthening the bond between Period and Cryptochrome. These findings help to demonstrate how Period proteins act as a timekeeper that regulates how long Cryptochrome can turn down the activity of CLOCK and BMAL1. A deeper understanding of the molecular choreography among the four clock proteins holds promise for developing medications to treat the sleep disorders and circadian clock disruptions associated with a modern lifestyle. DOI: http://dx.doi.org/10.7554/eLife.03674.002