Mutations in the chloroplast inner envelope protein TIC100 impair and repair chloroplast protein import and impact retrograde signaling.
Mutations in the chloroplast inner envelope protein TIC100 impair and repair chloroplast protein import and impact retrograde signaling.
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DOI：
10.1093/plcell/koac153
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发表时间：
2022-07-30
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--
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叶绿体的生物发生需要在核质和叶绿体本身中合成蛋白质。核编码的叶绿体蛋白通过细胞器被膜中的多蛋白转运子输入。关于由TIC20、TIC100和其他蛋白质组成的1-丙二醛复合体是否构成内膜TIC转位尚有争议。拟南芥Cue8绿色突变体在叶绿体发育过程中普遍存在缺陷。我们将CUE8确定为TIC100。Tic100cue8突变体积累了水平降低的1-丙二醛复合体成分，并减少了两种不同输入特征的核编码的叶绿体蛋白的输入。对tic100cue8抑制子的搜索发现了同一基因tic100soh1中的第二个突变，它挽救了可见的、1 丙二醛复合体亚基丰度和叶绿体蛋白输入表型。Tic100soh1保留但迅速退出绿化期，并挽救tic100cue8的合成致死性，当逆行信号因基因组解偶联1基因突变而受损时。除了强烈的绿色外，RNA编辑的变化和未进口前体蛋白的存在表明，当TIC100功能改变时，会触发强烈的信号响应。我们的结果与TIC100以及1-MDA复合体在叶绿体输入光合作用和非光合作用蛋白中的作用是一致的，这是一个启动逆行信号的过程。叶绿体内被膜TIC100的互补突变导致叶绿体蛋白输入的减少或纠正的改善，并突出了信号作用。
Chloroplast biogenesis requires synthesis of proteins in the nucleocytoplasm and the chloroplast itself. Nucleus-encoded chloroplast proteins are imported via multiprotein translocons in the organelle’s envelope membranes. Controversy exists around whether a 1-MDa complex comprising TIC20, TIC100, and other proteins constitutes the inner membrane TIC translocon. The Arabidopsis thaliana cue8 virescent mutant is broadly defective in plastid development. We identify CUE8 as TIC100. The tic100cue8 mutant accumulates reduced levels of 1-MDa complex components and exhibits reduced import of two nucleus-encoded chloroplast proteins of different import profiles. A search for suppressors of tic100cue8 identified a second mutation within the same gene, tic100soh1, which rescues the visible, 1 MDa complex-subunit abundance, and chloroplast protein import phenotypes. tic100soh1 retains but rapidly exits virescence and rescues the synthetic lethality of tic100cue8 when retrograde signaling is impaired by a mutation in the GENOMES UNCOUPLED 1 gene. Alongside the strong virescence, changes in RNA editing and the presence of unimported precursor proteins show that a strong signaling response is triggered when TIC100 function is altered. Our results are consistent with a role for TIC100, and by extension the 1-MDa complex, in the chloroplast import of photosynthetic and nonphotosynthetic proteins, a process which initiates retrograde signaling. Complementary mutations in TIC100 of the chloroplast inner envelope membrane cause reductions or corrective improvements in chloroplast protein import, and highlight a signaling role.
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影响因子：
64.8
作者：
Jumper J;Evans R;Pritzel A;Green T;Figurnov M;Ronneberger O;Tunyasuvunakool K;Bates R;Žídek A;Potapenko A;Bridgland A;Meyer C;Kohl SAA;Ballard AJ;Cowie A;Romera-Paredes B;Nikolov S;Jain R;Adler J;Back T;Petersen S;Reiman D;Clancy E;Zielinski M;Steinegger M;Pacholska M;Berghammer T;Bodenstein S;Silver D;Vinyals O;Senior AW;Kavukcuoglu K;Kohli P;Hassabis D
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Hassabis D
影响因子：
7.2
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56.9
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影响因子：
11.4
作者：
Heins, L;Mehrle, A;Soll, J
通讯作者：
Soll, J
影响因子：
4.5
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Chotewutmontri P;Barkan A
通讯作者：
Barkan A