AKINβγ contributes to SnRK1 heterotrimeric complexes and interacts with two proteins implicated in plant pathogen resistance through its KIS/GBD sequence
AKINβγ contributes to SnRK1 heterotrimeric complexes and interacts with two proteins implicated in plant pathogen resistance through its KIS/GBD sequence
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DOI：
10.1104/pp.106.087718
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发表时间：
2006-11-01
期刊：
影响因子：
7.4
通讯作者：
Thomas, Martine
中科院分区：
文献类型：
--
作者：
Gissot, Lionel;Polge, Cecile;Thomas, Martine
蔗糖非发酵-1蛋白激酶(SNF1)/AMP激活的蛋白激酶亚家族在营养和环境胁迫的代谢反应中起着核心作用。在酵母(酿酒酵母)和哺乳动物中，β-和γ-非催化亚基分别参与底物专一性和亚细胞定位以及对激酶活性的调节。以前在玉米(Zea Mays)中已经描述了非典型的β-伽马亚基，在其N端提供了与b-亚基特有的KIS(激酶相互作用序列)结构域相关的序列(Lumbrera等人，2001年)。已经提出了两个组分的存在，即含有BG亚基的SNF1相关蛋白激酶(SnRK1)复合体和一个SnRK1激酶。在这项工作中，我们发现，尽管拟南芥(Arabiopsis Thaliana)具有不寻常的特征，但类似于β-伽马的同源基因在体外和体内都明显与类似于β-亚基的亚基相互作用，这表明它参与了位于细胞质和细胞核中的异三聚体复合体。出乎意料的是，一项对AKINbg基因表达的转录分析强调了AKINbg基因表达调控中存在不同的剪接机制。以AKINbg为诱饵进行的双杂交筛选，结合植物双分子荧光互补实验，表明在细胞质中存在与病原菌抗性蛋白相关的两个富含亮氨酸的重复序列与阿金β-伽马之间的相互作用。有趣的是，这种相互作用通过截短的KIS结构域发生，该结构域与最近在哺乳动物和酵母中描述的GBD(糖原结合结构域)完全对应。一项系统发育研究表明，类似贝塔-伽马相关蛋白仅限于植物界。总之，这些数据表明存在植物特有的SnRK1三聚体复合体，推测它参与了植物特有的功能，如植物与病原菌的相互作用。
The sucrose nonfermenting-1 protein kinase (SNF1)/AMP-activated protein kinase subfamily plays a central role in metabolic responses to nutritional and environmental stresses. In yeast (Saccharomyces cerevisiae) and mammals, the beta-and gamma-noncatalytic subunits are implicated in substrate specificity and subcellular localization, respectively, and regulation of the kinase activity. The atypical beta gamma-subunit has been previously described in maize (Zea mays), presenting at its N-terminal end a sequence related to the KIS (kinase interacting sequence) domain specific to the b-subunits (Lumbreras et al., 2001). The existence of two components, SNF1-related protein kinase (SnRK1) complexes containing the bg-subunit and one SnRK1 kinase, had been proposed. In this work, we show that, despite its unusual features, the Arabidopsis (Arabidopsis thaliana) homolog AKIN beta gamma clearly interacts with AKIN beta-subunits in vitro and in vivo, suggesting its involvement in heterotrimeric complexes located in both cytoplasm and nucleus. Unexpectedly, a transcriptional analysis of AKINbg gene expression highlighted the implication of alternative splicing mechanisms in the regulation of AKINbg expression. A two-hybrid screen performed with AKINbg as bait, together with in planta bimolecular fluorescence complementation experiments, suggests the existence of interactions in the cytosol between AKIN beta gamma and two leucine-rich repeats related to pathogen resistance proteins. Interestingly, this interaction occurs through the truncated KIS domain that corresponds exactly to a GBD (glycogen-binding domain) recently described in mammals and yeast. A phylogenetic study suggests that AKIN beta gamma-related proteins are restricted to the plant kingdom. Altogether, these data suggest the existence of plant-specific SnRK1 trimeric complexes putatively involved in a plant-specific function such as plant-pathogen interactions.