X-ray structure of the dimeric cytochrome bc1 complex from the soil bacterium Paracoccus denitrificans at 2.7-Ã resolution

► First structure of fully active bacterial complex III at 2.7-Å resolution. ► Change of oligomerization state by truncation of acidic N-terminus of cytochrome c1. ► Comparison of complex III structures reveals structural differences in cytochrome c1. ► Model for the electron transfer complex with the native substrate cytochrome c552.