Post-translational control mechanisms of the circadian clock

生物钟的翻译后控制机制

• 批准号: 8626412
• 负责人: DAVID E SOMERS
• 金额: $ 29.23万
• 依托单位: OHIO STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-03-01 至 2015-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8626412
• 关键词: Address; Arabidopsis; Biological Models; Cell Cycle; Cell Nucleus; Circadian Rhythms; Client; Clock protein; Complex; Eukaryota; F-Box Proteins; Feedback; Gatekeeping; Genes; Genetic Transcription; Heat-Shock Proteins 90; Individual; Intracellular Transport; Lead; Link; Maintenance; Malignant Neoplasms; Messenger RNA; Modeling; Molecular; Nuclear; Nuclear Import; Nuclear Pore; Periodicity; Phase; Phosphoric Monoester Hydrolases; Phosphorylation; Phosphotransferases; Play; Process; Proteins; Recruitment Activity; Regulation; Role; Structure; System; Time; Translations; Validation; base; chaperonin; circadian pacemaker; design; heuristics; mRNA Export; mathematical model; molecular phenotype; mutant; nectin; novel; novel strategies; nucleocytoplasmic transport; protein protein interaction; public health relevance; transcription factor

DESCRIPTION (provided by applicant): This proposal is designed to investigate three different post-translational mechanisms of circadian clock control in Arabidopsis. The first is the role of protein phosphorylation, and the effect on activity, localization and stability of key clock proteins. Robust-phase specific phosphorylation of five key proteins in the Arabidopsis clock raises the question of its significance in their activity, localization and turnover. We will focus on the first validated phosphorylation-dependent protein-protein interaction in the Arabidopsis clock to begin to understand the dynamics of TOC1 and PRR3 post-translationally. Additionally, we propose a novel approach to discovering new kinases and phosphatases that act on clock proteins. We also propose to begin modeling this portion of the circadian system to address circuitry of the clock that is not based on transcription. The second is the effect chaperonins play in the maturation of the F-box protein ZEITLUPE to its functional state, necessary to the maintenance of robust circadian amplitude and period. We have identified two components new to any circadian system which likely contribute to ZTL maturation. Through effects on ZTL, these two components indirectly regulate the circadian system. The role of these two proteins in obtaining fully active ZTL, and their potential interaction is the underlying question addressed. The third mechanism is the role of the nuclear pore in the regulation of nuclear import/export of mRNA and/or protein of clock genes. The nuclear pore acts as a gatekeeper to the nucleus and all transcription factors and other regulators of nuclear function must pass through this highly complex structure. All eukaryotic circadian systems involve nucleocytoplasmic shuttling of mRNA and protein which may contribute substantially to establishing the timing delays necessary to establishing a 24 h molecular periodicity. We have identified a nuclear pore component that slows the circadian clock when absent. Understanding the molecular basis of this delay should lead to a greater understanding of how circadian timing is tied to intracellular transport. In a related way, the TOC1/PRR5 interaction appears to facilitate TOC1 nuclear entry and may also serve to recruit a kinase to the interaction. The molecular basis of this interaction and the effect on period will lead to increased understanding of the role of regulated nuclear entry in the clock. While the early heuristic models of the clock focused on transcription/translation feedback loops, recent findings across all circadian systems have highlighted the inadequacy of this view and how post- translational mechanisms contribute substantially to sustaining circadian oscillation. The studies described below will contribute to a greater understanding of circadian clock in particular, and to oscillatory feedback systems in general.

描述(申请人提供)：这项建议旨在研究拟南芥生物钟控制的三种不同的翻译后机制。第一个是蛋白质磷酸化的作用，以及对关键时钟蛋白活性、定位和稳定性的影响。拟南芥生物钟中五个关键蛋白的强健阶段特异性磷酸化提出了它在它们的活性、定位和周转中的重要性的问题。我们将把重点放在拟南芥时钟中第一个被证实的磷酸化依赖的蛋白质-蛋白质相互作用上，以开始了解TOC1和PRR3翻译后的动力学。此外，我们提出了一种新的方法来发现作用于时钟蛋白的新的激酶和磷酸酶。我们还建议开始对昼夜节律系统的这一部分进行建模，以解决不基于转录的时钟电路。第二个是伴侣蛋白在F-box蛋白ZEITLUPE成熟到其功能状态中所起的作用，这是维持强健的昼夜节律幅度和周期所必需的。我们已经确定了两个可能有助于ZTL成熟的新的昼夜节律系统的成分。这两种成分通过对ZTL的作用，间接调节昼夜节律系统。这两个蛋白质在获得完全活性ZTL中的作用以及它们之间的潜在相互作用是我们要解决的基本问题。第三种机制是核孔在调控Clock基因的mRNA和/或蛋白质的核进出口中的作用。核孔充当细胞核的把关人，所有转录因子和其他核功能调节因子都必须通过这个高度复杂的结构。所有真核生物的昼夜节律系统都涉及到核质内mRNA和蛋白质的穿梭，这可能在很大程度上有助于建立建立24小时分子周期所需的时间延迟。我们已经确定了一种核孔成分，当没有这种成分时，它会减缓生物钟的运行速度。了解这种延迟的分子基础应该会更好地理解昼夜节律是如何与细胞内运输联系在一起的。在一种相关的方式中，TOC1/PRR5的相互作用似乎促进了TOC1核的进入，也可能起到招募激酶到相互作用中的作用。这种相互作用的分子基础及其对周期的影响将使人们更好地理解受调控的核进入在生物钟中的作用。虽然早期的启发式时钟模型专注于转录/翻译反馈环，但最近在所有昼夜节律系统中的发现突显了这一观点的不足，以及翻译后机制如何对维持昼夜节律振荡做出实质性贡献。下面描述的研究将有助于更好地理解生物钟，特别是一般的振荡反馈系统。