The Structural and Biochemical Bases of Circadian Oscillator Rhythmicity

昼夜节律振荡器节律的结构和生化基础

• 批准号: 7677075
• 负责人: Andy LiWang
• 金额: $ 27.36万
• 依托单位: UNIVERSITY OF CALIFORNIA, MERCED
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-04-01 至 2011-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7677075
• 关键词: Active Sites; Address; Affect; Bacteria; Binding; Binding Sites; Biochemical; Biological; Biological Models; Buffers; C-terminal; Circadian Rhythms; Classification; Clock protein; Collaborations; Communication; Complex; Coupled; Coupling; Cyanobacterium; DNA Sequence Rearrangement; Daily; Distal; Enzymes; Event; Financial compensation; Frequencies; Goals; Health; Heart; Hour; Human; Kinetics; Laboratories; Localized; Measurement; Mediating; Modeling; Molecular; Molecular Conformation; Mutation; N-terminal; Organism; Pathway interactions; Periodicity; Phase; Phosphorylation; Phosphorylation Site; Play; Process; Proteins; Range; Rate; Reaction; Recombinants; Resistance; Resolution; Role; Site; Structure; Sunlight; Surface; Synechococcus; System; Temperature; Testing; Texas; Thinking; Time; Tube; Universities; Variant; base; circadian pacemaker; day; protein structure; reconstitution; research study

The central oscillators of circadian clocks of organisms ranging from bacteria to humans synchronize biological activities with daily changes in sunlight and temperature, and have been shown to be important to health and survival. The central oscillator can be thought of as the heart of the circadian clock. What is the basis of the self -sustained rhythmicity, why are the periods ~24 hours, and why are the frequencies of circadian clocks much more resistant than the rates of most enzymes to changes in temperature? These questions are fundamental to all circadian central oscillators. Our long-term goal is to provide comprehensive answers to these questions for a central oscillator of a model system at biochemical and structural resolution. The central oscillator of the circadian clock in the cyanobacterium Synechococcus elongatus is comprised of only three proteins, KaiA, KaiB, and KaiC. A simple mixture consisting of the recombinant forms of these clock proteins and ATP in a test tube can reconstitute a self-sustained and temperature-compensated circadian rhythm of KaiC phosphorylation over several cycles. A single cycle has two halves: an ~12 hour autophosphorylation phase and an ~12 hour autodephosphorylation phase. Alternating interactions of KaiC with KaiA and KaiB, respectively, slowly swing KaiC between hyper- and hypophosphorylation over each day. This central oscillator-in-a-tube provides an outstanding opportunity to answer the questions posed above and to develop a biochemically and structurally detailed understanding of a biological timekeeper. Our specific aims are the following: 1. Determine how KaiA sets the ~12-hour autophosphorylation phase of the clock period. 2. Determine how KaiB mediates the ~12 hour autodephosphorylation phase of the clock period. 3. Determine whether autophosphorylation and autodephosphorylation of KaiC are cooperative processes. Here, we address biochemically and structurally the problems of how the long ~24 hour period of the circadian rhythm is established, how that period is buffered against changes in temperature, and how an oscillator reverses direction after 12 hours.

从细菌到人类的生物体生物钟的中心振荡器 使生物活动与阳光和温度的每日变化同步， 已经被证明对健康和生存很重要。中央振荡器可以是 被认为是生物钟的核心。自立的基础是什么 节奏性，为什么周期是24小时，为什么昼夜节律的频率 生物钟比大多数酶对温度变化的抵抗力更强？ 这些问题是所有昼夜节律中心振荡器的基础。我们的长期目标 是提供全面的答案，这些问题的中心振荡器的 生物化学和结构分辨率的模型系统。 蓝细菌聚球藻生物钟的中心振荡器 细长体仅由三种蛋白质KaiA、KaiB和KaiC组成。简单混合物 由这些时钟蛋白和ATP的重组形式组成， 重建KaiC的自我维持和温度补偿的昼夜节律 磷酸化几个循环。一个周期有两个半：一个~12小时 自磷酸化阶段和约12小时的自去磷酸化阶段。交替 KaiC分别与KaiA和KaiB的相互作用，使KaiC在 高磷酸化和低磷酸化。 这个中央空调提供了一个绝佳的机会来回答 以上提出的问题，并制定一个生物化学和结构详细 了解生物计时器。我们的具体目标如下： 1.确定KaiA如何设置时钟的~12小时自磷酸化阶段 期 2.确定KaiB如何介导细胞凋亡的~12小时自动去磷酸化阶段。 时钟周期 3.确定KaiC的自身磷酸化和自身去磷酸化是否 合作进程。 在这里，我们解决生物化学和结构的问题，如何长~24小时 建立了昼夜节律的周期，该周期如何缓冲 温度的变化，以及振荡器如何在12小时后反转方向。