Recent advances in cytochrome bc1: Inter monomer electronic communication?

► We review recent genetic systems that use “one-plasmid” or “two-plasmids” to produce hetero-dimeric cytochrome bc1 enzymes. ► One-plasmid” system appears unstable, but might produce only a hetero-dimeric cytochrome bc1. ► “Two-plasmids” system is more stable, but it produces concomitantly a mixture of homo- and hetero-dimeric cytochrome bc1. ► Using the two-plasmids system, reliable evidence for occurrence of inter monomer electron transfer is emerging. ► Salient current issues on cytochrome bc1 structure and function are listed.