Tic12, a 12-kDa essential component of the translocon at the inner envelope membrane of chloroplasts in Arabidopsis
Tic12, a 12-kDa essential component of the translocon at the inner envelope membrane of chloroplasts in Arabidopsis
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Tic12，拟南芥叶绿体内包膜易位子的 12 kDa 重要组成部分
DOI：
10.1093/plcell/koac240
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Nakai Masato
中科院分区：
文献类型：
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作者：
Zhao Xueyang;Higa Takeshi;Nakai Masato
位于叶绿体外被膜的复合体translocon和位于叶绿体内被膜的复合体translocon（TIC）分别介导前蛋白跨叶绿体外被膜和内被膜的转运。Tic 20、Tic 56、Tic 100和Tic 214组成稳定的1兆道尔顿TIC，其功能是拟南芥和莱茵衣藻所必需的。Tic 20通过形成蛋白传导通道在前蛋白易位中起核心作用。Tic 56、Tic 100和Tic 214对于TIC功能也是不可或缺的，但这一过程是否需要其他组件尚不清楚。在这里，我们证明了一个12 kDa的蛋白质命名为Tic 12是TIC inA的一部分。thaliana，并参与前蛋白转运穿过内包膜膜。Tic 12与TIC紧密相关，但在高盐条件下与Triton X-100结合时解离。位点特异性UV交联实验表明，Tic 12和Tic 20直接与转运前蛋白的转运肽相互作用。与其他无效突变体类似，Thetic 12无效突变体对白化病和幼苗具有致死性。Tic 12和Tic 20也参与了豌豆叶绿体中前蛋白的转运。因此，Tic 12是与Tic 20一起构成1兆道尔顿TIC的功能核心的必要成分。
The complexes translocon at the outer envelope membrane of chloroplasts and translocon at the inner envelope membrane of chloroplasts (TIC) mediate preprotein translocation across the chloroplast outer and inner envelope membranes, respectively. Tic20, Tic56, Tic100, and Tic214 form a stable one-megadalton TIC whose function is essential forArabidopsis thalianaandChlamydomonas reinhardtii. Tic20 plays a central role in preprotein translocation by forming a protein-conducting channel. Tic56, Tic100, and Tic214 are also indispensable for TIC function, but whether other components are required for this process remain unclear. Here, we demonstrate that a 12-kDa protein named Tic12 is part of the TIC inA. thalianaand participates in preprotein translocation across the inner envelope membrane. Tic12 was tightly associated with the TIC but disassociated under high-salt conditions in combination with Triton X-100. Site-specific UV crosslinking experiments revealed that Tic12 and Tic20 directly interact with the transit peptide of a translocating preprotein. Thetic12null mutants are albino and seedling lethal, similar to the otherticnull mutants. Tic12 and Tic20 were also involved in preprotein translocation in (Pisum sativum) pea chloroplasts. Thus, Tic12 is an essential constituent that forms the functional core together with Tic20 in the one-megadalton TIC.