Zhao Dazhong, Ni Weimin, Feng Baomin, Han Tianfu, Petrasek Megan G, Ma Hong
Department of Biology and Huck Institute for Life Sciences, 313 Wartik Laboratory, The Pennsylvania State University, University Park, PA 16802, USA.
Plant Physiol. 2003 Sep;133(1):203-17. doi: 10.1104/pp.103.024703.
Ubiquitin-mediated proteolysis by the proteasome is a critical regulatory mechanism controlling many biological processes. In particular, SKP1, cullin/CDC53, F-box protein (SCF) complexes play important roles in selecting substrates for proteolysis by facilitating the ligation of ubiquitin to specific proteins. In plants, SCF complexes have been found to regulate auxin responses and jasmonate signaling and may be involved in several other processes, such as flower development, circadian clock, and gibberellin signaling. Although 21 Skp1-related genes, called Arabidopsis-SKP1-like (ASK), have been uncovered in the Arabidopsis genome, ASK1 is the only gene that has been analyzed genetically. As a first step toward understanding their functions, we tested for expression of 20 ASK genes using reverse transcription-polymerase chain reaction experiments. Also, we examined the expression patterns of 11 ASK genes by in situ hybridizations. The ASK genes exhibit a spectrum of expression levels and patterns, with a large subset showing expression in the flower and/or fruit. In addition, the ASK genes that have similar sequences tend to have similar expression patterns. On the basis of the expression results, we selectively suppressed the expression of a few ASK genes using RNA interference. Compared with the ask1 mutant, the strong ASK1 RNA interference (RNAi) line exhibited similar or enhanced phenotypes in both vegetative and floral development, whereas ASK11 RNAi plants had normal vegetative growth but mild defects in flower development. The diverse expression patterns and distinct defects observed in RNAi plants suggest that the ASK gene family may collectively perform a range of functions and may regulate different developmental and physiological processes.
蛋白酶体介导的泛素化蛋白水解是控制许多生物过程的关键调控机制。特别是，SKP1、cullin/CDC53、F-box蛋白（SCF）复合物通过促进泛素与特定蛋白质的连接，在选择蛋白水解底物方面发挥重要作用。在植物中，已发现SCF复合物调节生长素反应和茉莉酸信号传导，并可能参与其他一些过程，如开花发育、生物钟和赤霉素信号传导。尽管在拟南芥基因组中发现了21个与Skp1相关的基因，称为拟南芥Skp1样（ASK）基因，但ASK1是唯一经过遗传分析的基因。作为了解其功能的第一步，我们使用逆转录-聚合酶链反应实验检测了20个ASK基因的表达。此外，我们通过原位杂交检查了11个ASK基因的表达模式。ASK基因表现出一系列表达水平和模式，其中很大一部分在花和/或果实中表达。此外，具有相似序列的ASK基因往往具有相似的表达模式。根据表达结果，我们使用RNA干扰选择性地抑制了一些ASK基因的表达。与ask1突变体相比，强ASK1 RNA干扰（RNAi）株系在营养和花发育方面表现出相似或增强的表型，而ASK11 RNAi植物营养生长正常，但花发育存在轻微缺陷。在RNAi植物中观察到的不同表达模式和明显缺陷表明，ASK基因家族可能共同发挥一系列功能，并可能调节不同的发育和生理过程。
