Oligomers of Tha4 organize at the thylakoid Tat translocase during protein transport
Oligomers of Tha4 organize at the thylakoid Tat translocase during protein transport
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DOI：
10.1074/jbc.m512453200
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发表时间：
2006-03-03
影响因子：
4.8
通讯作者：
Cline, K
中科院分区：
文献类型：
--
作者：
Dabney-Smith, C;Mori, H;Cline, K
类囊体和细菌的Tat（双精氨酸易位）系统在不破坏膜的渗透屏障的情况下运输完全折叠的蛋白质底物。类囊体系统的两个组分，cpTatC和Hcf106，组成一个前体结合受体复合物。第三个组分，Tha4，与前体结合受体复合物组装在一起进行易位步骤，并且被认为至少组成了部分蛋白质传导通道。在这里，我们使用了两种不同的交联方法来探索th4在转位酶中的组织。这些交联技术表明，过渡到活跃的蛋白质运输状态导致th4两亲螺旋和c端尾部结构域对齐，形成th4低聚物。寡聚化需要功能性的Tha4、双精氨酸信号肽和活性的cpTatC-Hcf106受体复合物。所得的低聚物的光谱与前体的成熟折叠结构域无关。我们提出了一种易位的活板门机制，即th4两亲螺旋的排列寡聚物折叠到膜上，允许前体蛋白通过。
The Tat ( twin arginine translocation) systems of thylakoids and bacteria transport fully folded protein substrates without breaching the permeability barrier of the membrane. Two components of the thylakoid system, cpTatC and Hcf106, compose a precursor-bound receptor complex. The third component, Tha4, assembles with the precursor-bound receptor complex for the translocation step and is thought to compose at least part of the protein-conducting channel. Here, we used two different cross-linking approaches to explore the organization of Tha4 in the translocase. These cross-linking techniques showed that transition to an active protein transport state resulted in an alignment of the Tha4 amphipathic helix and C-terminal tail domains to form Tha4 oligomers. Oligomerization required functional Tha4, a twin arginine signal peptide, and an active cpTatC-Hcf106 receptor complex. The spectrum of oligomers obtained was independent of the mature folded domain of the precursor. We propose a trapdoor mechanism for translocation whereby aligned oligomers of Tha4 amphipathic helices fold into the membrane to allow formfitting passage of precursor proteins.