Post-translational control mechanisms of the circadian clock

生物钟的翻译后控制机制

• 批准号: 8427363
• 负责人: DAVID E SOMERS
• 金额: $ 28.22万
• 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 2015-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8427363
• 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（由申请人提供）：该提案旨在研究拟南芥中昼夜节律控制的三种不同的翻译后机制。首先是蛋白质磷酸化的作用，以及对关键时钟蛋白的活性，定位和稳定性的影响。拟南芥中五个关键蛋白的鲁棒相特异性磷酸化提出了其在活动，定位和周转中的重要性问题。我们将重点关注拟南芥时钟中首次经过验证的磷酸化依赖性蛋白 - 蛋白质相互作用，以开始在翻译后开始理解TOC1和PRR3的动力学。此外，我们提出了一种新的方法，用于发现对时钟蛋白作用的新型激酶和磷酸酶。我们还建议开始对昼夜节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成熟到其功能状态的影响，这对于维持稳健的昼夜节律幅度和周期所必需。我们已经确定了任何昼夜节律系统的新组件，这可能有助于ZTL成熟。通过对ZTL的影响，这两个组成部分间接调节了昼夜节律系统。这两种蛋白质在获得完全活跃的ZTL及其潜在相互作用中的作用是解决的基本问题。 第三个机制是核孔在调节时钟基因的mRNA和/或蛋白质的核进出口中的作用。核孔充当核的守门人，所有转录因子和核功能的其他调节剂必须通过这种高度复杂的结构。所有真核生物昼夜节律系统均涉及mRNA和蛋白质的核细胞穿梭，这可能有助于确定建立24小时分子周期性所需的时机延迟。我们已经确定了一个核孔成分，该核孔成分在不存在时会减慢昼夜节律。理解这种延迟的分子基础，应进一步了解昼夜节律与细胞内转运的关系。以一种相关的方式，TOC1/PRR5相互作用似乎促进了TOC1核进入，并且也可能有助于募集激酶与相互作用。这种相互作用的分子基础和对周期的影响将导致人们对被调节的核进入时钟的作用的了解增加。 尽管时钟的早期启发式模型集中在转录/翻译反馈循环上，但所有昼夜节律系统的最新发现突显了这种观点的不足以及后翻译机制如何对维持昼夜节律的振荡产生重大贡献。下面描述的研究将有助于对昼夜节律的更深入了解，以及一般而言的振荡反馈系统。