The ubiquitin system is crucial for the development and fitness of higher plants. De-etiolation, during which green plants initiate photomorphogenesis and establish autotrophy, is a dramatic and complicated process that is tightly regulated by a massive number of ubiquitylation/de-ubiquitylation events. Here we present site-specific quantitative proteomic data for the ubiquitylomes of de-etiolating seedling leaves of Zea mays L. (exposed to light for 1, 6, or 12 h) achieved through immunoprecipitation-based high-resolution mass spectrometry (MS). Through the integrated analysis of multiple ubiquitylomes, we identified and quantified 1926 unique ubiquitylation sites corresponding to 1053 proteins. We analyzed these sites and found five potential ubiquitylation motifs, KA, AXK, KXG, AK, and TK. Time-course studies revealed that the ubiquitylation levels of 214 sites corresponding to 173 proteins were highly correlated across two replicate MS experiments, and significant alterations in the ubiquitylation levels of 78 sites (fold change >1.5) were detected after de-etiolation for 12 h. The majority of the ubiquitylated sites we identified corresponded to substrates involved in protein and DNA metabolism, such as ribosomes and histones. Meanwhile, multiple ubiquitylation sites were detected in proteins whose functions reflect the major physiological changes that occur during plant de-etiolation, such as hormone synthesis/signaling proteins, key C4 photosynthetic enzymes, and light signaling proteins. This study on the ubiquitylome of the maize seedling leaf is the first attempt ever to study the ubiquitylome of a C4 plant and provides the proteomic basis for elucidating the role of ubiquitylation during plant de-etiolation.

中文翻译：

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玉米去迷迭香过程中泛素化事件的大规模鉴定和时程定量。

泛素系统对于高等植物的发育和适应性至关重要。在绿色植物启动光形态发生并建立自养过程中，去黄酮化是一个引人注目的复杂过程，受到大量泛素化/去泛素化事件的严格控制。在这里，我们介绍了通过基于免疫沉淀的高分辨率质谱（MS）实现的玉米（Zea mays L.）去苗化幼苗叶片泛光的部位特异性定量蛋白质组学数据（暴露于光1、6或12 h）。通过对多个泛素化基因组的综合分析，我们鉴定并量化了1926个独特的泛素化位点，对应于1053个蛋白质。我们分析了这些位点，发现了五个潜在的泛素化基序，KA，AXK，KXG，AK和TK。时程研究表明，在两次重复的MS实验中，与173个蛋白相对应的214个位点的泛素化水平高度相关，并且在去异位12 h后检测到78个位点的泛素化水平发生了显着变化（倍数变化> 1.5）。 。我们确定的大多数泛素化位点对应于参与蛋白质和DNA代谢的底物，例如核糖体和组蛋白。同时，在蛋白质中检测到多个泛素化位点，这些蛋白质的功能反映了植物去特异化过程中发生的主要生理变化，例如激素合成/信号蛋白，关键的C4光合酶和光信号蛋白。