Intrinsically Unstructured Phosphoprotein TSP9 Regulates Light Harvesting in Arabidopsis thaliana
Intrinsically Unstructured Phosphoprotein TSP9 Regulates Light Harvesting in Arabidopsis thaliana
复制标题
DOI：
10.1021/bi8016334
复制
发表时间：
2009-01-20
期刊：
影响因子：
2.9
通讯作者：
Vener, Alexander V.
中科院分区：
文献类型：
--
作者：
Fristedt, Rikard;Carlberg, Inger;Vener, Alexander V.
9 kDa的类囊体可溶性磷蛋白TSP 9是一种本质上非结构化的植物特异性蛋白[Song，J.，等人（2006）Biochemistry 45，15633-15643]，其功能未知，但与捕光蛋白和两种光系统的外围建立了关联[Hansson，M.，等人（2007）J.Biol.Chem.282，16214-16222]。为了研究该蛋白的功能，我们在拟南芥中使用了反向遗传学和生化及荧光测量方法相结合的方法。使用24000个拟南芥基因的阵列的T-DNA插入TSP 9基因的植物的差异基因表达分析揭示了一组特定的主要信号传导和未知蛋白质的高光依赖性诱导的消失。TSP 9缺陷型植物体内捕光复合物II多肽的磷酸化水平降低。重组TSP 9磷酸化光的类囊体膜分离的野生型和突变体植物缺乏STN 8蛋白激酶，但不是由类囊体缺乏STN 7激酶，光合状态转换所必需的。TSP 9缺失突变体和TSP 9下调的RNAi植物表现出进行状态转换的能力降低。非光化学猝灭的叶绿素荧光在高的光强度也是效率较低的突变体相比，野生型植物。类囊体膜蛋白复合物的蓝色天然电泳显示，TSP 9缺乏增加光系统II二聚体和超复合物的相对稳定性。可以得出结论，TSP 9调节植物光捕获作为一种膜结合蛋白，促进光系统II的光捕获蛋白的解离。
Thylakoid-soluble phosphoprotein of 9 kDa, TSP9, is an intrinsically unstructured plant-specific protein [Song, J., et al. (2006) Biochemistry 45, 15633-15643] with unknown function but established associations with light-harvesting proteins and peripheries of both photosystems [Hansson, M., et al. (2007) J. Biol. Chem. 282, 16214-16222]. To investigate the function of this protein, we used a combination of reverse genetics and biochemical and fluorescence measurement methods in Arabidopsis thaliana. Differential gene expression analysis of plants with a T-DNA insertion in the TSP9 gene using an array of 24000 Arabidopsis genes revealed disappearance of high light-dependent induction of a specific set of mostly signaling and unknown proteins. TSP9-deficient plants had reduced levels of in vivo phosphorylation of light-harvesting complex II polypeptides. Recombinant TSP9 was phosphorylated in light by thylakoid membranes isolated from the wild-type and mutant plants lacking STN8 protein kinase but not by the thylakoids deficient in STN7 kinase, essential for photosynthetic state transitions. TSP9-lacking mutant and RNAi plants with downregulation of TSP9 showed reduced ability to perform state transitions. The nonphotochemical quenching of chlorophyll fluorescence at high light intensities was also less efficient in the mutant compared to wild-type plants. Blue native electrophoresis of thylakoid membrane protein complexes revealed that TSP9 deficiency increased relative stability of photosystem II dimers and supercomplexes. It is concluded that TSP9 regulates plant light harvesting acting as a membrane-binding protein facilitating dissociation of light-harvesting proteins from photosystem II.