An NMR-based docking model for the physiological transient complex between cytochrome f and cytochrome c6

The physiological transient complex between cytochrome f (Cf) and cytochrome c6 (Cc6) from the cyanobacterium Nostoc sp. PCC 7119 has been analysed by NMR spectroscopy. The binding constant at low ionic strength is 8 ± 2 mM−1, and the binding site of Cc6 for Cf is localized around its exposed haem edge. On the basis of the experimental data, the resulting docking simulations suggest that Cc6 binds to Cf in a fashion that is analogous to that of plastocyanin but differs between prokaryotes and eukaryotes.