ジャーナル: Sci Adv / 年: 2026 タイトル: Structural remodeling of the mitochondrial protein biogenesis machinery under proteostatic stress. 著者: Kenneth Ehses / Jorge P López-Alonso / Odetta Antico / Yannik Lang / Till Rudack / Abdussalam Azem / Miratul M K Muqit / Iban Ubarretxena-Belandia / Rubén Fernández-Busnadiego / 要旨: Cells have evolved organelle-specific responses to maintain protein homeostasis (proteostasis). During proteostatic stress, mitochondria down-regulate translation and enhance protein folding, yet the ...Cells have evolved organelle-specific responses to maintain protein homeostasis (proteostasis). During proteostatic stress, mitochondria down-regulate translation and enhance protein folding, yet the underlying mechanisms remain poorly defined. Here, we used cryo-electron tomography to observe the structural consequences of mitochondrial proteostatic stress within human cells. We detected protein aggregates within the mitochondrial matrix, accompanied by a marked remodeling of cristae architecture. Concomitantly, the number of mitochondrial ribosome complexes was significantly reduced. Mitochondrial Hsp60 (mHsp60), a key protein folding machine, underwent major conformational changes to favor complexes with its co-chaperone mHsp10. We visualized the interactions of mHsp60 with native substrate proteins and determined in vitro mHsp60 cryo-electron microscopy structures enabling nucleotide state assignment of the in situ structures. These data converge on a model of the mHsp60 functional cycle and its essential role in mitochondrial proteostasis. More broadly, our findings reveal structural mechanisms governing mitochondrial protein biosynthesis and their remodeling under proteostatic stress.
凍結剤: ETHANE-PROPANE / チャンバー内温度: 310 K / 装置: FEI VITROBOT MARK IV / 詳細: Backside blotting.
詳細
Cells directly grown on EM grids
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電子顕微鏡法
顕微鏡
TFS KRIOS
撮影
フィルム・検出器のモデル: FEI FALCON IV (4k x 4k) 平均電子線量: 4.0 e/Å2 詳細: For subtomogram averaging, only the first 20 frames were used. The total dose per tilt-series equals 150e/A2.