A dicistronic construct for the expression of functional spinach chloroplast ferredoxin:thioredoxin reductase in <i>Escherichia coli</i>

Ferredoxin:thioredoxin reductase (FTR) is a heterodimeric Fe---S containing disulfide reductase involved in the light-dependent activation of photosynthetic enzymes. We have designed a dicistronic construct for the heterologous expression of this nucleus encoded chloroplast protein in <i>Escherichia coli</i>. The coding sequences for the two mature subunits have been inserted in tandem into the expression vector pET-3d. This dicistronic construct is correctly translated yielding soluble, perfectly functional FTR. The recombinant enzyme is composed of both subunits, contains the correctly inserted Fe---S cluster as evidenced by its spectral properties and is indistinguishable from the enzyme isolated from leaves in its capacity to activate chloroplast fructose-1,6-bisphosphatase, one of the well known light activated enzymes of the Calvin cycle.