The role of SPY and its TPR domain in the regulation of gibberellin action throughout the life cycle of Petunia hybrida plants
The role of SPY and its TPR domain in the regulation of gibberellin action throughout the life cycle of Petunia hybrida plants
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DOI：
10.1046/j.1365-313x.2001.01144.x
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发表时间：
2001-10-01
期刊：
影响因子：
7.2
通讯作者：
Weiss, D
中科院分区：
文献类型：
--
作者：
Izhaki, A;Swain, SM;Weiss, D
SPY在拟南芥中作为赤霉素（GA）作用的负调节因子，但其作用方式和调控机制尚不清楚。SPY在转基因矮牵牛植株中的过表达影响了各种GA调节的过程，包括种子萌发、芽伸长、花起始、花发育和GA诱导的基因GIP的表达。当用GA生物合成抑制剂多效唑处理野生型矮牵牛植株时，获得了类似的表型。SPY的N端含有三肽重复序列（TPR）。TPR基序参与蛋白质-蛋白质相互作用，表明SPY是多蛋白复合物的一部分。为了验证这一假设，我们在转基因矮牵牛中过量表达了SPY的TPR区域而没有催化结构域，并产生了显性负性SPY突变体。转基因种子能够在多效唑上萌发，表明GA信号增强。我们克隆了矮牵牛SPY同源物PhSPY，并表明其mRNA水平不受GA或ABA的影响。本研究的结果支持SPY作为GA作用的负调节因子的作用，表明TPR结构域是与其他蛋白质相互作用形成活性复合物所必需的，并表明不同植物使用相似的机制来转导GA信号。
SPY acts as a negative regulator of gibberellin (GA) action in Arabidopsis, but its mode of action and regulation are still unknown. SPY over-expression in transgenic petunia plants affected various GA-regulated processes, including seed germination, shoot elongation, flower initiation, flower development and the expression of a GA-induced gene, GIP, A similar phenotype was obtained when wild-type petunia plants were treated with the GA-biosynthesis inhibitor, paclobutrazol. The N-terminus of SPY contains tetratricopeptide repeats (TPR). TPR motifs participate in protein-protein interactions, suggesting that SPY is part of a multiprotein complex. To test this hypothesis, we over-expressed the SPY's TPR region without the catalytic domain in transgenic petunia and generated a dominant-negative SPY mutant. The transgenic seeds were able to germinate on paclobutrazol, suggesting an enhanced GA signal. We cloned the petunia SPY homologue, PhSPY, and showed that its mRNA level is not affected by GA or ABA. The results of this study support the role of SPY as a negative regulator of GA action, suggest that the TPR domain is required for the interaction with other proteins to form an active complex and indicate that different plants use similar mechanisms to transduce the GA signal.