論文 - 詳細
| RRC ID | 54610 |
|---|---|
| 著者 | Chen YL, Chen LJ, Chu CC, Huang PK, Wen JR, Li HM. |
| タイトル | TIC236 links the outer and inner membrane translocons of the chloroplast. |
| ジャーナル | Nature |
| Abstract |
The two-membrane envelope is a defining feature of chloroplasts. Chloroplasts evolved from a Gram-negative cyanobacterial endosymbiont. During evolution, genes of the endosymbiont have been transferred to the host nuclear genome. Most chloroplast proteins are synthesized in the cytosol as higher-molecular-mass preproteins with an N-terminal transit peptide. Preproteins are transported into chloroplasts by the TOC and TIC (translocons at the outer- and inner-envelope membranes of chloroplasts, respectively) machineries1,2, but how TOC and TIC are assembled together is unknown. Here we report the identification of the TIC component TIC236; TIC236 is an integral inner-membrane protein that projects a 230-kDa domain into the intermembrane space, which binds directly to the outer-membrane channel TOC75. The knockout mutation of TIC236 is embryonically lethal. In TIC236-knockdown mutants, a smaller amount of the inner-membrane channel TIC20 was associated with TOC75; the amount of TOC-TIC supercomplexes was also reduced. This resulted in a reduced import rate into the stroma, though outer-membrane protein insertion was unaffected. The size and the essential nature of TIC236 indicate that-unlike in mitochondria, in which the outer- and inner-membrane translocons exist as separate complexes and a supercomplex is only transiently assembled during preprotein translocation3,4-a long and stable protein bridge in the intermembrane space is required for protein translocation into chloroplasts. Furthermore, TIC236 and TOC75 are homologues of bacterial inner-membrane TamB5 and outer-membrane BamA, respectively. Our evolutionary analyses show that, similar to TOC75, TIC236 is preserved only in plants and has co-evolved with TOC75 throughout the plant lineage. This suggests that the backbone of the chloroplast protein-import machinery evolved from the bacterial TamB-BamA protein-secretion system. |
| 巻・号 | 564(7734) |
| ページ | 125-129 |
| 公開日 | 2018-12-1 |
| DOI | 10.1038/s41586-018-0713-y |
| PII | 10.1038/s41586-018-0713-y |
| PMID | 30464337 |
| MeSH | Arabidopsis / cytology* Arabidopsis / metabolism Arabidopsis Proteins / genetics Arabidopsis Proteins / metabolism* Bacterial Outer Membrane Proteins / metabolism Chloroplast Proteins / genetics Chloroplast Proteins / metabolism* Chloroplasts / genetics Chloroplasts / metabolism* Escherichia coli Proteins / metabolism Evolution, Molecular Intracellular Membranes / metabolism* Membrane Proteins / genetics Membrane Proteins / metabolism* Membrane Transport Proteins / genetics Membrane Transport Proteins / metabolism* Multiprotein Complexes / genetics Multiprotein Complexes / metabolism Mutation Peas / cytology Protein Binding Protein Precursors / metabolism Protein Transport |
| IF | 43.07 |
| 引用数 | 15 |
| オルトメトリクス指標 |
オルトメトリクス指標項目
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| 最多言及媒体 | X(Twitter) |
| 各媒体での言及数の合計 | 42 |
| 過去6か月間でのオルトメトリクス指標の変動値 | 0.0 |
| リソース情報 | |
| シロイヌナズナ / 植物培養細胞・遺伝子 | pda00216 |