Laboratory of Plant Molecular Biology, Mendel University in Brno, Zemědělská 1, CZ-61300 Brno, Czech Republic.
J Exp Bot. 2011 Jan;62(3):921-37. doi: 10.1093/jxb/erq322. Epub 2010 Oct 25.
Cytokinins are plant hormones involved in regulation of diverse developmental and physiological processes in plants whose molecular mechanisms of action are being intensely researched. However, most rapid responses to cytokinin signals at the proteomic and phosphoproteomic levels are unknown. Early cytokinin responses were investigated through proteome-wide expression profiling based on image and mass spectrometric analysis of two-dimensionally separated proteins and phosphoproteins. The effects of 15 min treatments of 7-day-old Arabidopsis thaliana seedlings with four main cytokinins representing hydroxyisopentenyl, isopentenyl, aromatic, and urea-derived type cytokinins were compared to help elucidate their common and specific function(s) in regulating plant development. In proteome and phosphoproteome maps, significant differences were reproducibly observed for 53 and 31 protein spots, respectively. In these spots, 96 proteins were identified by matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry (MALDI-TOF/TOF MS), providing a snapshot of early links in cytokinin-regulated signalling circuits and cellular processes, including light signalling and photosynthesis, nitrogen metabolism, the CLAVATA pathway, and protein and gene expression regulation, in accordance with previously described cytokinin functions. Furthermore, they indicate novel links between temperature and cytokinin signalling, and an involvement of calcium ions in cytokinin signalling. Most of the differentially regulated proteins and phosphoproteins are located in chloroplasts, suggesting an as yet uncharacterized direct signalling chain responsible for cytokinin action in chloroplasts. Finally, first insights into the degree of specificity of cytokinin receptors on phosphoproteomic effects were obtained from analyses of cytokinin action in a set of cytokinin receptor double mutants.
细胞分裂素是参与植物多种发育和生理过程调节的植物激素，其作用的分子机制正在被深入研究。然而，大多数对细胞分裂素信号在蛋白质组学和磷酸蛋白质组学水平的快速反应仍然未知。通过基于二维分离蛋白质和磷酸蛋白质的图像和质谱分析的全蛋白质组表达谱，研究了早期细胞分裂素的反应。用代表羟基异戊烯基、异戊烯基、芳基和脲衍生型细胞分裂素的四种主要细胞分裂素处理 7 天大的拟南芥幼苗 15 分钟，比较其对植物发育的共同和特定功能，以帮助阐明它们的共同和特定功能。在蛋白质组和磷酸蛋白质组图谱中，分别可重复性地观察到 53 和 31 个蛋白质斑点的显著差异。在这些斑点中，通过基质辅助激光解吸/电离飞行时间/飞行时间质谱（MALDI-TOF/TOF MS）鉴定了 96 种蛋白质，提供了细胞分裂素调节信号转导和细胞过程的早期联系的快照，包括光信号和光合作用、氮代谢、CLAVATA 途径以及蛋白质和基因表达调控，与先前描述的细胞分裂素功能一致。此外，它们表明了温度与细胞分裂素信号之间的新联系，以及钙离子在细胞分裂素信号中的参与。大多数差异调节的蛋白质和磷酸蛋白质位于叶绿体中，这表明存在尚未被描述的直接信号链，负责细胞分裂素在叶绿体中的作用。最后，从一组细胞分裂素受体双突变体中分析细胞分裂素的作用，获得了关于细胞分裂素受体在磷酸蛋白质组学效应上的特异性程度的初步见解。
