The architecture of respiratory supercomplexes Journal Article

Author(s): Letts, James A.; Fiedorczuk, Karol; Sazanov, Leonid A
Article Title: The architecture of respiratory supercomplexes
Affiliation IST Austria
Abstract: Mitochondrial electron transport chain complexes are organized into supercomplexes responsible for carrying out cellular respiration. Here we present three architectures of mammalian (ovine) supercomplexes determined by cryo-electron microscopy. We identify two distinct arrangements of supercomplex CICIII 2 CIV (the respirasome) - a major 'tight' form and a minor 'loose' form (resolved at the resolution of 5.8 Å and 6.7 Å, respectively), which may represent different stages in supercomplex assembly or disassembly. We have also determined an architecture of supercomplex CICIII 2 at 7.8 Å resolution. All observed density can be attributed to the known 80 subunits of the individual complexes, including 132 transmembrane helices. The individual complexes form tight interactions that vary between the architectures, with complex IV subunit COX7a switching contact from complex III to complex I. The arrangement of active sites within the supercomplex may help control reactive oxygen species production. To our knowledge, these are the first complete architectures of the dominant, physiologically relevant state of the electron transport chain.
Keywords: Mammalia; Ovis
Journal Title: Nature
Volume: 537
Issue 7622
ISSN: 0028-0836
Publisher: Nature Publishing Group  
Date Published: 2016-01-01
Start Page: 644
End Page: 648
Sponsor: We thank the MRC LMB Cambridge for the use of the Titan Krios microscope. Data processing was performed using the IST high-performance computer cluster. J.A.L. holds a long-term fellowship from FEBS. K.F. is partially funded by a MRC UK PhD fellowship.
DOI: 10.1038/nature19774
Open access: no