Genetic and Physical Interaction Studies Reveal Functional Similarities between ALBINO3 and ALBINO4 in Arabidopsis.
Genetic and Physical Interaction Studies Reveal Functional Similarities between ALBINO3 and ALBINO4 in Arabidopsis.
复制标题
遗传和物理相互作用研究揭示了拟南芥中 ALBINO3 和 ALBINO4 之间的功能相似性。
DOI：
10.1104/pp.15.00376
复制
发表时间：
2015
期刊：
影响因子：
7.4
通讯作者：
Trösch R
中科院分区：
文献类型：
--
作者：
Trösch R
ALBINO_3(ALB3)是类囊体蛋白靶向复合体的已知成分，它与叶绿体信号识别颗粒(CpSRP)和cpSRP受体--叶绿体丝状温度敏感Y(CpFtsY)相互作用。它的蛋白质插入功能主要是针对捕光的复杂蛋白质而建立的，这些蛋白质首先与独特的叶绿体cpSRP43组分相互作用，然后通过依赖于GTP的cpSRP-cpFtsY相互作用被运送到ALB3整合酶。在拟南芥中，后来发现的ALB3同源物ALB4被认为不参与捕光复杂蛋白的靶向，而是参与ATP合成酶复合体的稳定。然而，在这里，我们证明了ALB3和ALB4有显著的功能重叠，并且这两种蛋白质都是有效插入细胞色素和潜在的含色素蛋白复合体的其他亚单位所必需的。ALB4和ALB3之间的遗传和物理相互作用，以及ALB4和cpSRP之间的物理相互作用，表明这两个ALB蛋白可能为其特定功能发挥了相似的相互作用。我们认为，ALB4通过参与某些底物(如细胞色素和Rieske蛋白)的ALB3-cpSRP途径，优化了类囊体蛋白的插入。尽管ALB4在招募伴侣的C-末端结构域方面明显与ALB3背道而驰，但我们的分析表明，一个可能的cpSRP结合基序并未完全丢失。
ALBINO3 (ALB3) is a well-known component of a thylakoid protein-targeting complex that interacts with the chloroplast signal recognition particle (cpSRP) and the cpSRP receptor, chloroplast filamentous temperature-sensitive Y (cpFtsY). Its protein-inserting function has been established mainly for light-harvesting complex proteins, which first interact with the unique chloroplast cpSRP43 component and then are delivered to the ALB3 integrase by a GTP-dependent cpSRP-cpFtsY interaction. In Arabidopsis (Arabidopsis thaliana), a subsequently discovered ALB3 homolog, ALB4, has been proposed to be involved not in light-harvesting complex protein targeting, but instead in the stabilization of the ATP synthase complex. Here, however, we show that ALB3 and ALB4 share significant functional overlap, and that both proteins are required for the efficient insertion of cytochromefand potentially other subunits of pigment-bearing protein complexes. Genetic and physical interactions between ALB4 and ALB3, and physical interactions between ALB4 and cpSRP, suggest that the two ALB proteins may engage similar sets of interactors for their specific functions. We propose that ALB4 optimizes the insertion of thylakoid proteins by participating in the ALB3-cpSRP pathway for certain substrates (e.g. cytochromefand the Rieske protein). Although ALB4 has clearly diverged from ALB3 in relation to the partner-recruiting C-terminal domain, our analysis suggests that one putative cpSRP-binding motif has not been entirely lost.