Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestr. 3, CH-3012, Bern, Switzerland.
Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestr. 3, CH-3012, Bern, Switzerland.
Mol Biochem Parasitol. 2021 Jul;244:111393. doi: 10.1016/j.molbiopara.2021.111393. Epub 2021 Jun 29.
Mitochondrial protein import depends on heterooligomeric translocases in the outer and inner membranes. Using import substrates consisting of various lengths of the N-terminal part of mitochondrial dihydrolipoamide dehydrogenase (LDH) fused to dihydrofolate reductase we present an in vivo analysis showing that in Trypanosoma brucei at least 96 aa of mature LDH are required to efficiently produce an import intermediate that spans both translocases. This is different to yeast, where around 50 aa are sufficient to achieve the same task and likely reflects the different arrangement and architecture of the trypanosomal mitochondrial translocases. Furthermore, we show that formation of the stuck import intermediate leads to a strong growth inhibition suggesting that, depending on the length of the LDH, the import channels in the translocases are quantitatively blocked.
线粒体蛋白的输入依赖于外膜和内膜中的异源寡聚体转位酶。我们使用由融合了二氢叶酸还原酶的各种长度的线粒体二氢硫辛酰胺脱氢酶（LDH）的 N 端部分组成的输入底物，进行了体内分析，结果表明，在布氏锥虫中，至少需要 96 个成熟 LDH 的氨基酸残基才能有效地产生跨越两种转位酶的输入中间产物。这与酵母不同，酵母中大约 50 个氨基酸残基就足以完成同样的任务，这可能反映了锥虫线粒体转位酶的不同排列和结构。此外，我们还表明，形成卡住的输入中间产物会导致强烈的生长抑制，这表明，根据 LDH 的长度，转位酶中的输入通道会被定量阻断。
