Cryo-EM structures of mitochondrial respiratory complex I from Drosophila melanogaster

Elife. 2023 Jan 9:12:e84424. doi: 10.7554/eLife.84424.


Respiratory complex I powers ATP synthesis by oxidative phosphorylation, exploiting the energy from NADH oxidation by ubiquinone to drive protons across an energy-transducing membrane. Drosophila melanogaster is a candidate model organism for complex I due to its high evolutionary conservation with the mammalian enzyme, well-developed genetic toolkit, and complex physiology for studies in specific cell types and tissues. Here, we isolate complex I from Drosophila and determine its structure, revealing a 43-subunit assembly with high structural homology to its 45-subunit mammalian counterpart, including a hitherto unknown homologue to subunit NDUFA3. The major conformational state of the Drosophila enzyme is the mammalian-type 'ready-to-go' active resting state, with a fully ordered and enclosed ubiquinone-binding site, but a subtly altered global conformation related to changes in subunit ND6. The mammalian-type 'deactive' pronounced resting state is not observed: in two minor states, the ubiquinone-binding site is unchanged, but a deactive-type π-bulge is present in ND6-TMH3. Our detailed structural knowledge of Drosophila complex I provides a foundation for new approaches to disentangle mechanisms of complex I catalysis and regulation in bioenergetics and physiology.

Keywords: D. melanogaster; NADH:ubiquinone oxidoreductase; enzyme mechanism; mitochondria; molecular biophysics; oxidative phosphorylation; structural biology.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cryoelectron Microscopy
  • Drosophila melanogaster* / metabolism
  • Electron Transport Complex I* / metabolism
  • Electron Transport Complex I* / ultrastructure
  • Mitochondria / metabolism
  • Ubiquinone / metabolism


  • Electron Transport Complex I
  • Ubiquinone