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Figure 1
Cryo-EM density maps of respiratory complex III from Y. lipolytica at 2.0 Å resolution (a) (combined data sets; the position of the lipid bilayer is indicated by grey lines) and 3.3 Å resolution (b) (+atovaquone+antimycin A) with the three subunits Cyt1, Rip1 and Cob that form the catalytic core and all seven supernumerary subunits found in yeasts. The solvent-exposed domain of the Rieske iron–sulfur protein was not resolved in the consensus refinement of all data sets of samples without added inhibitor (a), whereas it was fixed in the b position (red, with the [2Fe–2S] cluster in yellow and orange) by the Pf-type inhibitor atovaquone (b). The lower panels show ligand densities after the refinement of individual data sets (c, d). After its addition, decylubiquinol was resolved in the Qi site, while density in the Qo site remained poorly defined. The inhibitor antimycin A displaced decylubiquinol from the Qi site when both were added (c). Atovaquone and antimycin A were resolved in the Qo and Qi sites, respectively, in the 3.3 Å resoution map (d). All maps were sharpened by a B factor of −30 Å2.

IUCrJ
Volume 10| Part 1| January 2023| Pages 27-37
ISSN: 2052-2525
https://doi.org/10.1107/S2052252522010570