ジャーナル: Nat Commun / 年: 2023 タイトル: Structures of Tetrahymena thermophila respiratory megacomplexes on the tubular mitochondrial cristae. 著者: Fangzhu Han / Yiqi Hu / Mengchen Wu / Zhaoxiang He / Hongtao Tian / Long Zhou / 要旨: Tetrahymena thermophila, a classic ciliate model organism, has been shown to possess tubular mitochondrial cristae and highly divergent electron transport chain involving four transmembrane protein ...Tetrahymena thermophila, a classic ciliate model organism, has been shown to possess tubular mitochondrial cristae and highly divergent electron transport chain involving four transmembrane protein complexes (I-IV). Here we report cryo-EM structures of its ~8 MDa megacomplex IV+ (I + III+ II), as well as a ~ 10.6 MDa megacomplex (IV + I + III+ II) at lower resolution. In megacomplex IV+ (I + III+ II), each CIV protomer associates one copy of supercomplex I + III and one copy of CII, forming a half ring-shaped architecture that adapts to the membrane curvature of mitochondrial cristae. Megacomplex (IV+ I + III+ II) defines the relative position between neighbouring half rings and maintains the proximity between CIV and CIII cytochrome c binding sites. Our findings expand the current understanding of divergence in eukaryotic electron transport chain organization and how it is related to mitochondrial morphology.