NdhS interacts with cytochrome b 6 f to form a complex in Arabidopsis.

Cyclic electron transport (CET) around photosystem I (PSI) is crucial for photosynthesis to perform photoprotection and sustain the balance of ATP and NADPH. However, the critical component of CET, cyt b 6 f complex (cyt b 6 f), functions in CET has yet to be understood entirely. In this study, we found that NdhS, a subunit of NADPH dehydrogenase-like (NDH) complex, interacted with cyt b 6 f to form a complex in Arabidopsis. This interaction depended on the N-terminal extension of NdhS, which was conserved in eukaryotic plants but defective in prokaryotic algae. The migration of NdhS was much more in cyt b 6 f than in PSI-NDH super-complex. Based on these results, we suggested that NdhS and NADP + oxidoreductase provide a docking domain for the mobile electron carrier ferredoxin to transfer electrons to the plastoquinone pool via cyt b 6 f in eukaryotic photosynthesis.