Cellular and biochemical context of Arabidopsis circadian-clock components

拟南芥的生物钟驱动着大约10,000个转录本的转录节奏，这协调了植物生长和发育的大部分方面。早花3号是昼夜信号的关键枢纽，它是时钟工作所必需的。我们最近发现ELF3作为ELF4配体和LUX DNA结合蛋白的物理积分器，一起被称为Evening Complex(EC)，这是振荡器循环和介导转录靶标抑制所必需的。因此，EC被认为是一个全球转录共抑制因子。由于ELF3基因编码了一种未知的生化和细胞活动的蛋白质，它如何在时钟维护中发挥关键作用仍然是个谜。我们已经证明的是，光信号可以抑制ELF3功能，这在决定振荡器速度对光的亮度做出反应方面具有至关重要的作用。ELF3与光敏色素B光感受器结合，我们证明这是一个失活事件。通过PhyB抑制ELF3抑制以加速昼夜节律的光信号的机制基础是这项工作的目标。我们将采用技术和主题相结合的方法来解决这些问题。我们提出了一系列实验，通过ELF3对环境光的响应来解开时钟重置机制，以了解其作用模式。结合生化、细胞和系统生物学实验，我们将研究ELF3的时空功能，并与其功能所需的其他成分进行比较。我们将研究ELF4在哪里激活ELF3的本地化背景，以及光敏色素如何抑制这一点。将对现有模型进行新的基因测试，以探索现有的明确假设，这些假设存在于生成当前昼夜节律系统模型的数学方程中。由于EC组件的基因测试显示，它们在调控靶点和生长发育方面具有非多余的作用，我们将监测这些染色质相关因子的全球、全基因组结合，以确定它们的非重叠靶标，以揭示它们协同调控转录靶基因的能力与差异调控转录靶基因的能力的基础。综上所述，我们预计这项提议的努力将为时钟社区中一个长期存在的问题提供机械基础，在这个问题中，光的感知导致周期的加速。这是一种时钟重置机制，对它的理解将帮助我们为新的纬度和生长高度量身定做作物。

The Arabidopsis circadian clock drives transcriptional rhythms of about 10,000 transcripts and this coordinates most aspects of plant growth and development. EARLY FLOWERING 3 is the key hub for diurnal signalling and it is required for the clock to work. We recently showed that ELF3 acts as a physical integrator for the ELF4 ligand and the LUX DNA-binding protein, together termed the Evening Complex (EC), and that this is required for the oscillator to cycle and to mediate repression of transcriptional targets. The EC was thus hypothesized to be a global transcriptional co-repressor. As the ELF3 gene encodes a protein of unknown biochemical and cellular activity, it has remained enigmatic as to how it performs its key role in clock maintenance. What we have shown is that light signalling can repress ELF3 function, and this has a crucial role in determining oscillator speed in response to the brightness of light. ELF3 binds the phytochrome B photoreceptor and we showed that this acts as an inactivation event. The mechanistic bases by which light signals through phyB inactivate ELF3 repression to accelerate circadian timing are the goals of this work. Integrated technical and thematic approaches would be used to tackle these questions.We propose a set of experiments to unravel the clock-resetting mechanism through ELF3 in response to ambient light in order to understand its mode of action. Using a combination of biochemical, cellular and systems biology experiments, we will examine the spatial-temporal function of ELF3 with a comparison to that of other components it requires for function. We will examine the localisation context of where ELF4 activates ELF3 and how phytochrome represses this. New genetic tests of existing models will be performed to probe the existing explicit hypotheses that exist within the mathematical equations that generate the current circadian-systems models. As genetic tests of EC components revealed a non-redundant action in their regulation of targets and growth and development, we will monitor the global, genome-wide binding of these chromatin-associated factors to define their non-overlapping targets to unravel the basis for their capacity to cooperatively versus differentially regulate transcriptional target genes. Taken together we envisage that the efforts of this proposal will provide the mechanistic basis of a long-standing problem in the clock community where light perception leads to acceleration of periodicity. This is a clock-resetting mechanism and its understanding will help us tailor crops for new latitudes and altitudes of growth.