Histone deacetylases regulating the diurnal transcriptome of maize

基因转录的昼夜调节是植物最基本的调控过程之一。被激活的基因与细胞核中的蛋白质紧密结合，形成一种叫做染色质的浓缩结构。近年来的研究强调了染色质修饰在这些基因调控中的作用。我们研究基因调控的模型是玉米中的C4光合作用，因为编码该途径的酶的基因以高水平表达，并显示出受多种刺激的复杂调控。在DFG资助的前三个项目中，我们建立了一个染色质模型作为信号集成器，允许植物存储有关细胞代谢状态，组织身份，昼夜节律控制和照明的信息。特别是，我们确定了特定的组蛋白乙酰化位点，上调照明。基于先前的结果，我们假设这种上调是通过抑制组蛋白去乙酰化酶（HDAC）引起的。在这个项目中，我们的目标是确定负责HDAC的表征玉米株系与个体HDAC的表达抑制。该项目将扩展到全转录组分析，以确定所选HDAC的所有靶基因。我们将通过染色质免疫沉淀分析野生型和突变体植物中这些基因的启动子染色质。此外，我们将产生过表达与蛋白质标签融合的所选HDAC的转基因玉米植物。这将使得能够直接分析染色质结合位点。这些研究将为单子叶植物基因表达的表观遗传控制和C4光合作用的调控提供新的见解。

Diurnal regulation of gene transcription is among the most basal regulatory processes in plants. The genes to be activated are packed with proteins in the cell nucleus in a condensed structure called chromatin. Research in recent years has highlighted the role of chromatin modifications in the regulation of these genes. Our model for studying gene regulation is C4 photosynthesis in maize, because the genes encoding the enzymes of this pathway are expressed at high levels and show a complex regulation by multiple stimuli. During three previous projects funded by the DFG, we established a model of chromatin as a signal integrator that allows plants to store information about the metabolic state of the cell, tissue identity, circadian control, and illumination. Particularly, we identified specific histone acetylation sites that are up-regulated upon illumination. Based on previous results, we hypothesize that this up-regulation is brought about by suppression of a histone deacetylase (HDAC). In this project, we aim at identifying the responsible HDAC by characterization of maize lines with suppressed expression of individual HDACs. The project will be extended to a whole transcriptome analysis in order to identify all target genes of the selected HDACs. We will analyse the promoter chromatin of these genes in wildtype and mutant plants by chromatin immunoprecipitation. Furthermore, we will generate transgenic maize plants that overexpress the selected HDACs fused to a protein tag. This will enable direct analysis of chromatin binding sites. These studies will allow new insights into the epigenetic control of gene expression in monocots and the regulation of C4 photosynthesis.