Structural basis for the isotype-specific interactions of ferredoxin and ferredoxin: NADP oxidoreductase: an evolutionary switch between photosynthetic and heterotrophic assimilation.

In higher plants, ferredoxin (Fd) and ferredoxin-NADP reductase (FNR) are each present as distinct isoproteins of photosynthetic type (leaf type) and non-photosynthetic type (root type). Root-type Fd and FNR are considered to facilitate the electron transfer from NADPH to Fd in the direction opposite to that occurring in the photosynthetic processes. We previously reported the crystal structure of the electron transfer complex between maize leaf FNR and Fd (leaf FNR:Fd complex), providing insights into the molecular interactions of the two proteins.