Structures of Tetrahymena thermophila respiratory megacomplexes on the tubular mitochondrial cristae.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 37248254.
- Also identified by DOI 10.1038/s41467-023-38158-5 and PMC identifier 10227065.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
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<sub>2 </sub>+ (I + III<sub>2 </sub>+ II)<sub>2</sub>, as well as a ~ 10.6 MDa megacomplex (IV<sub>2</sub> + I + III<sub>2 </sub>+ II)<sub>2</sub> at lower resolution. In megacomplex IV<sub>2 </sub>+ (I + III<sub>2 </sub>+ II)<sub>2</sub>, each CIV<sub>2</sub> protomer associates one copy of supercomplex I + III<sub>2</sub> and one copy of CII, forming a half ring-shaped architecture that adapts to the membrane curvature of mitochondrial cristae. Megacomplex (IV<sub>2 </sub>+ I + III<sub>2 </sub>+ II)<sub>2</sub> defines the relative position between neighbouring half rings and maintains the proximity between CIV<sub>2</sub> and CIII<sub>2</sub> 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.
Medical subject headings
- Tetrahymena thermophila