8B6J

Cryo-EM structure of cytochrome bc1 complex (complex-III) from respiratory supercomplex of Tetrahymena thermophila

Summary for 8B6J

• Entry DOI: 10.2210/pdb8b6j/pdb
• EMDB information: 15868
• Descriptor: Peptidase M16 inactive domain protein, UQCRTT3/UP1, Transmembrane protein, putative, ... (19 entities in total)
• Functional Keywords: ciliate, mitochondrial, cytochrome bc1, supercomplex, electron transport
• Biological source: Tetrahymena thermophila SB210; More
• Total number of polymer chains: 24
• Total formula weight: 695465.30

Authors

Muhleip, A.,Kock Flygaard, R.,Amunts, A. (deposition date: 2022-09-27, release date: 2023-03-29, Last modification date: 2023-04-12)

Primary citation

Muhleip, A.,Flygaard, R.K.,Baradaran, R.,Haapanen, O.,Gruhl, T.,Tobiasson, V.,Marechal, A.,Sharma, V.,Amunts, A.
Structural basis of mitochondrial membrane bending by the I-II-III 2 -IV 2 supercomplex.
Nature, 615:934-938, 2023

PubMed Abstract: Mitochondrial energy conversion requires an intricate architecture of the inner mitochondrial membrane. Here we show that a supercomplex containing all four respiratory chain components contributes to membrane curvature induction in ciliates. We report cryo-electron microscopy and cryo-tomography structures of the supercomplex that comprises 150 different proteins and 311 bound lipids, forming a stable 5.8-MDa assembly. Owing to subunit acquisition and extension, complex I associates with a complex IV dimer, generating a wedge-shaped gap that serves as a binding site for complex II. Together with a tilted complex III dimer association, it results in a curved membrane region. Using molecular dynamics simulations, we demonstrate that the divergent supercomplex actively contributes to the membrane curvature induction and tubulation of cristae. Our findings highlight how the evolution of protein subunits of respiratory complexes has led to the I-II-III-IV supercomplex that contributes to the shaping of the bioenergetic membrane, thereby enabling its functional specialization.

PubMed: 36949187
DOI: 10.1038/s41586-023-05817-y

Experimental method

ELECTRON MICROSCOPY (2.8 Å)