Fig. 2.

Electron paths in hybrid fusion complexes with various cofactor knockout patterns. (A) B_S–B complex contains all electronic connections characteristic of native cytochrome bc₁ (see Fig. 1A). (B and C) Symmetric patterns disrupt all connections between the Q_o and Q_i sites. (D–F) Three variants of asymmetric patterns cross-inactivate the complex and leave one possible connection between the Q_o and Q_i sites (involving the inter-monomer electron transfer). Orange and blue show two halves of the fusion protein corresponding to cytochromes b of R. sphaeroides and R. capsulatus, respectively. Red crosses indicate cofactor knockouts.