Circadian Progams in Bacteria

昼夜节律是人类健康的重要组成部分，它调节睡眠、警觉性， 激素、各种组织的代谢活动以及许多其他生物过程。最终 对昼夜节律振荡器的机制的解释将需要表征生物钟的结构，功能， 以及这些时钟的分子组成的相互作用。目前的项目是阐明基本的 生物钟原理在生物物理/分子水平的模型系统，原核生物 蓝藻，其中遗传/生物化学研究已经确定了三个关键的时钟蛋白，KaiA，KaiB， KaiC这三种蛋白质可以在体外重建昼夜节律振荡器。这一惊人的发现 导致我们重新评估对所有生物体（包括哺乳动物）的生物钟的理解。 KaiA、KaiB和KaiC蛋白质的晶体结构已经被确认--这些是第一个时钟 确定蛋白质的三维结构。分子的原子分辨率结构的出现 时钟装置的组成部分标志着昼夜节律研究的一个戏剧性的分水岭， 昼夜节律机制的分析。目前的项目将确定核心的分子基础 生物物理学、遗传学和结构学的方法。特别是，（i） KaiA/KaiB/KaiC复合物的节律性形成，与（ii）KaiC磷酸化的节律性相比， 将评估计时机制中的关键齿轮。生物物理/分子分析将结合 用数学建模来确定基本参数。温度补偿， 生物钟将通过筛选体内温度依赖性突变体， 体外分析最后，这个核心发条和基因的全球协调之间的联系 通过测试新的“非线性”模型，将阐明日常周期的表达，该模型提出， 核心发条通过调节染色体拓扑结构有节奏地调节启动子活性， 昼夜节律的功能。 与公共卫生的相关性：该项目将在分子水平上阐明昼夜节律机制， 在此之前是无法实现的。生物钟对心理健康至关重要。此外，本发明还提供了一种方法， 生物钟是在轮班工作和“时差”条件下获得最佳表现的关键， 占美国劳动力的比例。对昼夜节律机制的认识沿着 适当调整睡眠阶段的治疗方法将使我们能够提高他们的表现、警觉性和幸福感。 轮班工人和旅行者，以及改善抑郁症患者的生活质量。

Circadian (daily) rhythms are a crucial component of human health that regulates sleep, alertness, hormones, metabolic activities of various tissues, and many other biological processes. The ultimate explanation for the mechanism of circadian oscillators will require characterizing the structures, functions, and interactions of the molecular components of these clocks. The current project is to elucidate the basic principles of circadian clocks at a biophysical/molecular level in a model system, the prokaryotic cyanobacteria, where genetic/biochemical studies have identified three key clock proteins, KaiA, KaiB, and KaiC. These three proteins can reconstitute a circadian oscillator in vitro. This remarkable observation has led to a re-evaluation of our understanding of circadian clocks in all organisms, including mammals. The crystal structure of the KaiA, KaiB, and KaiC proteins have been reported-these are the first clock proteins to have their 3-D structures determined. The advent of atomic resolution structures of the molecular components of a clockwork marks a dramatic watershed in circadian research by ushering in truly molecular analyses of circadian mechanisms. The current project will determine the molecular basis of the core clockwork by biophysical, genetic, and structural approaches. In particular, the relative roles of (i) the rhythmic formation of a KaiA/KaiB/KaiC complex as compared with (ii) the rhythm of KaiC phosphorylation as the key cogs in the timing mechanism will be assessed. The biophysical/molecular analyses will be coupled with mathematical modeling to determine the essential parameters. Temperature compensation of this biological clock will be investigated by screening for temperature dependent mutants in vivo followed by in vitro analyses. Finally, the linkage between this core clockwork and the global orchestration of gene expression over the daily cycle will be illuminated by testing the novel "oscilloid" model, which proposes that the core clockwork rhythmically regulates promoter activity by modulating chromosomal topology as a function of circadian time. RELEVANCE TO PUBLIC HEALTH: This project will clarify circadian mechanisms at molecular levels that were heretofore unattainable. Biological clocks have been found to be crucial for mental health. In addition, biological clocks are key for optimal performance under shiftwork and "jet-lag" conditions that affect a large proportion of the USA workforce. Knowledge of the circadian mechanism along with the development of therapies to properly phase sleep will allow us to enhance the performance, alertness, and well-being of shiftworkers and travelers in addition to improving the quality of life for depressed subjects.