Soluble domains of cytochrome c-556 and Rieske iron–sulfur protein from Chlorobaculum tepidum: Crystal structures and interaction analysis

The synergy between the PscC subunits for electron transfer to the P840 special pair in Chlorobaculum tepidum

“…This is an indication that when the reaction center is accepting electrons from the docked PscC, the distant PscC could be accessible to receive electrons from menaquinol: cyt c oxidoreductase or cyt c-554/555 (Tsukatani et al 2008 ). This finding is in contrast to the proposed electron transfer pathway directly from the Rieske/cyt b -type complex via membrane-anchored cyt c -556 (CT0073) and from thiosulfate (S 2 O 3 2− ) oxidation via cyt c -554 (CT0075) to one of the two monomeric PscC subunits (Kishimoto et al 2023 ). Flash-induced absorption changes indicated that the photo-oxidized PscC can accept electrons from both the menaquinol: cyt c oxidoreductase and the cyt c-554/555 independently (Tsukatani et al 2008 ).…”

“…As mentioned above the electron donors for the PscC subunits are the membrane-bound cytochrome c-556 and the water-soluble c-554 cytochrome. To be able to confirm which of the conformations we observed can receive electrons, docking experients with the known structure of both cytochromes were performed (Yu et al 2013 ; Kishimoto et al 2023 ). The docking calculation shows that only the distant cytochrome is accessible and only this cytochrome shows consistent protein interactions with both electron donors (Fig.…”