Light Responsive Genes

描述(申请人提供)：光是调节植物发育和新陈代谢过程的重要信号。感受不同波长光的光感受器在拟南芥中已被鉴定。其中，被远红光激活的光敏色素A(PhyA)已经成为在幼苗去黄化过程中起主要作用的光感受器。我们的长期目标是确定和表征参与PHYA信号转导的信号中间体和机制，以实现下游发育反应。为此，我们已经确定了在PhyA信号转导中有缺陷的突变体PAT和LafA。我们将集中于识别PAT和LAF蛋白的生化作用机制，以及它们如何与PhyA信号网络中的其他中间体起作用。特别是，我们感兴趣的是PhyA信号如何修饰这些蛋白质并调节它们的丰度。一个主要的焦点是研究MYB型转录激活因子LAF1、其下游靶标和相互作用蛋白的调控。我们已经证明COP1是光形态发生的抑制因子，是一种E3连接酶，在体外可以泛化LAF1。将在体外和转基因植物中研究COP1介导的泛素化在PhyA信号转导中对LAF1的调节。蛋白质通过小泛素样修饰物(SUMO)的结合正在成为一种重要的信号调节机制。我们有间接证据表明，LAF1可以被求和化，因为它与COP1共定位在核斑点中，这是一种与相扑共轭相关的亚核定位模式。我们将研究SUMO化在LAF1调节和PHEA反应传递中的作用。我们将分析的另一个突变体是pat1，它属于植物特有的GRAS信号调节家族。PAT1和它的同源基因SCL21在PHYA信号转导中可能存在的冗余功能关系将被研究。第三个基因PAT3和相近的同源基因PAT3h似乎只参与PhyA信号反应的一个子集。我们将详细描述这些基因在PhyA信号转导中的作用。对上述蛋白质的鉴定将揭示先前未知的PHYA信号转导机制。

DESCRIPTION (provided by applicant): Light is an important signal for regulation of plant development and metabolic processes. The photoreceptors for perception of different wavelengths of light have been characterized in Arabidopsis. Amongst these, phytochrome A (phyA), which is activated by far-red light, has emerged as the photoreceptor that plays a major role in seedling de-etiolation. Our long-term objective is to identify and characterize the signaling intermediates and mechanisms involved in transduction of the phyA signal to enable downstream developmental responses. To this end, we have identified mutants pat and lafdefective in phyA signaling. We will focus on identification of the biochemical mechanisms of action of PAT and LAF proteins and how they act with other intermediates in the phyA signaling network. In particular, we are interested in how phyA signals modify these proteins and regulate their abundance. A major focus is to study the regulation of the myb-type transcription activator, LAF1, its downstream targets and interacting proteins. We have shown that COP1, a repressor of photomorphogenesis, is an E3 ligase and can ubiquitinate LAF1 in vitro. The regulation of LAF1 by COP1-mediated ubiquitination in phyA signaling will be investigated in vitro and in transgenic plants. Conjugation of proteins by SUMO (small ubiquitin-like modifier) is emerging as an important regulatory mechanism of signaling. We have indirect evidence that LAF1 could be sumoylated as it is co-localized with COP1 in nuclear speckles, a subnuclear localization pattern associated with SUMO conjugation. We will investigate the role of sumoylation in LAF1 regulation and transmission of phyA responses. The other mutant we will analyze is pat1, which belongs to the plant-specific GRAS family of signal regulators. The possible redundant functional relationship between PAT1 and its close homolog SCL21 in phyA signaling will be examined. A third gene PAT3 and a close homolog PAT3h seem to participate only in a subset of phyA signaling responses. We will characterize the role of these genes in detail in the phyA signal transduction. Characterization of the above proteins will uncover previously unknown mechanisms of phyA signal transduction.