Regulation of photosynthetic electron flow on dark to light transition by ferredoxin:NADP(H) oxidoreductase interactions.

During photosynthesis, electron transport is necessary for carbon assimilation and must be regulated to minimize free radical damage. There is a longstanding controversy over the role of a critical enzyme in this process (ferredoxin:NADP(H) oxidoreductase, or FNR), and in particular its location within chloroplasts. Here we use immunogold labelling to prove that FNR previously assigned as soluble is in fact membrane associated.

Ferredoxin:NADP(H) Oxidoreductase Abundance and Location Influences Redox Poise and Stress Tolerance.

In linear photosynthetic electron transport, ferredoxin:NADP(H) oxidoreductase (FNR) transfers electrons from ferredoxin (Fd) to NADP Both NADPH and reduced Fd (Fd) are required for reductive assimilation and light/dark activation/deactivation of enzymes. FNR is therefore a hub, connecting photosynthetic electron transport to chloroplast redox metabolism. A correlation between FNR content and tolerance to oxidative stress is well established, although the precise mechanism remains unclear.

N-terminal structure of maize ferredoxin:NADP+ reductase determines recruitment into different thylakoid membrane complexes.

To adapt to different light intensities, photosynthetic organisms manipulate the flow of electrons through several alternative pathways at the thylakoid membrane. The enzyme ferredoxin:NADP(+) reductase (FNR) has the potential to regulate this electron partitioning because it is integral to most of these electron cascades and can associate with several different membrane complexes. However, the factors controlling relative localization of FNR to different membrane complexes have not yet been established.