GUN1 Controls Accumulation of the Plastid Ribosomal Protein S1 at the Protein Level and Interacts with Proteins Involved in Plastid Protein Homeostasis
GUN1 Controls Accumulation of the Plastid Ribosomal Protein S1 at the Protein Level and Interacts with Proteins Involved in Plastid Protein Homeostasis
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DOI：
10.1104/pp.15.02033
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发表时间：
2016-03-01
期刊：
影响因子：
7.4
通讯作者：
Leister, Dario
中科院分区：
文献类型：
--
作者：
Tadini, Luca;Pesaresi, Paolo;Leister, Dario
叶绿体的发育或代谢变化会对植物细胞的其他部分产生深远的影响。这种细胞内反应与起源于叶绿体的信号相关，并将其生理状态的信息传递到细胞核，这导致基因表达的大规模变化（逆行信号）。一个旨在识别逆行信号成分的筛选导致了所谓的基因组非偶联（枪）突变体的发现。遗传学证据表明，叶绿体蛋白GUN1整合来自扰动的信号在质体氧化还原状态，质体基因表达，和四吡咯生物合成（TPB）在拟南芥（拟南芥）幼苗，发挥叶绿体功能的生物控制。然而，GUN1在叶绿体中整合逆行信号的分子机制尚不清楚。在这里，我们表明，GUN1也在成年植物中发挥作用，有助于叶绿体的操作控制。gun1突变与叶绿体核糖体蛋白S1（PRPS1）和L11的基因突变在遗传上相互作用。gun1 prps1系的分析表明，GUN1控制PRPS1在蛋白质水平的积累。基于免疫共沉淀实验，GUN1蛋白与参与叶绿体蛋白质稳态的蛋白质物理相互作用。此外，酵母双杂交和双分子荧光互补实验表明，GUN1可能与几种TPB酶，包括镁螯合酶亚基D（CHLD）和其他两种已知激活逆行信号的TPB酶瞬时相互作用。此外，PRPS1和CHLD与蛋白质复合物的结合受到GUN 1的调节。这些发现使我们能够推测逆行信号可能涉及GUN1依赖性蛋白复合物的形成。
Developmental or metabolic changes in chloroplasts can have profound effects on the rest of the plant cell. Such intracellular responses are associated with signals that originate in chloroplasts and convey information on their physiological status to the nucleus, which leads to large-scale changes in gene expression (retrograde signaling). A screen designed to identify components of retrograde signaling resulted in the discovery of the so-called genomes uncoupled (gun) mutants. Genetic evidence suggests that the chloroplast protein GUN1 integrates signals derived from perturbations in plastid redox state, plastid gene expression, and tetrapyrrole biosynthesis (TPB) in Arabidopsis (Arabidopsis thaliana) seedlings, exerting biogenic control of chloroplast functions. However, the molecular mechanism by which GUN1 integrates retrograde signaling in the chloroplast is unclear. Here we show that GUN1 also operates in adult plants, contributing to operational control of chloroplasts. The gun1 mutation genetically interacts with mutations of genes for the chloroplast ribosomal proteins S1 (PRPS1) and L11. Analysis of gun1 prps1 lines indicates that GUN1 controls PRPS1 accumulation at the protein level. The GUN1 protein physically interacts with proteins involved in chloroplast protein homeostasis based on coimmunoprecipitation experiments. Furthermore, yeast two-hybrid and bimolecular fluorescence complementation experiments suggest that GUN1 might transiently interact with several TPB enzymes, including Mg-chelatase subunit D (CHLD) and two other TPB enzymes known to activate retrograde signaling. Moreover, the association of PRPS1 and CHLD with protein complexes is modulated by GUN1. These findings allow us to speculate that retrograde signaling might involve GUN1-dependent formation of protein complexes.