Electron flow during photosynthesis is regulated by location of Ferredoxin:NADP(H) Oxidoreductase

During photosynthesis, electron transport is necessary for carbon
assimilation and must be regulated to minimise 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. We
combined this technique with a genetic approach in the model plant
Arabidopsis, to show that the distribution of this enzyme between
different membrane regions depends on its interaction with specific tether
proteins. We further demonstrate a correlation between this distribution
and the activity of different photosynthetic electron transport pathways.
This supports a role for FNR location in regulating photosynthetic
electron flow.